For example, if the bunker produces $140k of product in ~3hrs(I haven't logged in today, so just using those #s...) then yes, it produces ~$777/min. However, not only does this not take into account the resupply delivery time(purchasing has a wait for delivery) nor the sale time, but it also assumes you are at the bunker at the exact moment the product fills. Which, unless you are sitting there waiting for it to do so(and of course losing money doing so, as you could be doing I/E, CEO/VIP work, etc rather than standing there doing nothing waiting for it to fill the last bit,) will likely never happen. For example, if the bunker hits the $140k while you are in the middle of an I/E mission on the other end of the map, it could take you 10+ minutes to finish the mission and travel to the bunker, plus the sale time before the profit is realised. Could be easily 20-25 minutes by the time the sale is complete, turning your 3 hours into 3h25m and the associated $/min changes to $683/min. Boom! Just lost over 12% per min from the rate.
See what I mean? The $/min is only relevant to the amount of time you are active in earning the money, because the amount of time between the moment you hit the 'purchase supplies' button and when the product matures(aka, complete your sale) is nearly never going to be the same. Similarly, whether you get the 1 drop off or 5 drop off missions, which vehicle, etc ALL changes the actual $/min. Accordingly, it should have no impact upon your grind routine.
What is important to consider, is how much time YOU spend ACTIVE to generate income through the various methods available, how you utilise the cooldowns effectively for those activities, and of course which of these activities you prefer. Folks may recall, no matter how you mix and match the top earning activities; profits tend to remain near $200k/hr of activity on average. Some hours(like the one you sell your bunker, for example) will earn greater than $200k, but then some will earn less as you spend time sourcing vehicles to replace ones you just sold, etc. However, most methods still hover near that amount. Going back to my 3-hour grind post the other day(which subsequently and suspiciously appeared, with some more liberal edits but nearly line for line on another forum just a few hours later.....for the second time.....) even the 25% increase in production speed still only produces one sale in that 3 hour grind. The 25% increase means that you will get one extra sale every 6 hours of grinding over the original production speed, and two extra sales every 10 hours of consecutive grinding(the fifth sale would complete somewhere in the 10th hour between 9hr1min after your grind began and completing the 10th hour.) Big time! You still only get one sale in a 3 hour cycle, but now you can get three sales in a 6 hour cycle, and four sales in a 9 hour cycle. Since very few people grind consecutively for that long, it really makes very little difference for most. The practical benefit folks will realise, though; is rather than getting in an extra sale every play session(again, not many people grind for 6 hours...) you should now be able to make two sales in ~4 hours rather than having to wait until just after the 5th hour begins before completing your second sale. Of course, all of this assumes that supply deliveries take ZERO minutes(they don't) and that you are always at the bunker and ready to sell the moment the product hits $140k....so....basically unattainable. The reality, with resupply latency and sale mission completion time is probably closer to one sale in a 3 hour cycle, with the second sale completing near the termination of the 4th hour and the third sale occurring somewhere just after the beginning of the 6th hour. That is still assuming you arrive at the bunker within a few minutes of production reaching $140k.
Now, back to my original point, which is to encourage folks to look at their grind routine in a more practical manner with the reality of what they are doing. As such, when considering these passive earners, the time to fill production(and accordingly, my previous paragraph) should be irrelevant to your decision on what to grind. In fact, without experimenting, the 25% production time reduction has the potential to cause you to actually make LESS in a particular 3 hour grind cycle. This probably confuses some folks, so I'll illustrate. If in that three hour grind cycle you were previously able to sell an average of 2 I/E cars per hour for each of the 3 hours, along with selling a bunker load in the 3rd hour the progress likely looks as follows;
1st hour - Buy supplies, source and sell 2 cars, use remaining 15+ minutes or so(I/E cooldown) to do VIP work and sell a Sentinel, etc
2nd hour - Source and sell a car in the first 10 minutes of the hour, then have 50 minutes to source/sell two more cars plus VIP/Sentinel, etc
3rd hour - Buy supplies, sell bunker, resupply biker business, sell biker, possibly source/sell one car plus limited VIP/Sentinel
And now it may be more like;
1st hour - Buy supplies, source and sell 2 cars, use remaining 15+ minutes or so(I/E cooldown) to do VIP work and sell a Sentinel, etc
2nd hour - Source and sell a car in the first 10 minutes of the hour, source another 20 minutes later, then buy supplies and sell bunker
3rd hour - Resupply biker business, sell biker, source/sell one car plus limited VIP/Sentinel
As you can see, while yes you sold the bunker in the 2nd hour instead of the 3rd, it caused you to miss out on sourcing/selling a third car in the 2nd hour. Being that a biker sale is typically 15-20 minutes, it is very unlikely that you will have time to be able to make that up by sourcing/selling a second car before the 3rd hour terminates. So, naturally you actually made less money because in this 3 hour cycle you sold one less I/E car yet made the same $ amount from the bunker, just an hour earlier. If you get lucky and get the single van biker sale mission, or perhaps the two motorcycles; you might be able to make that time up and get a second car sold in the third hour, but that van mission comes up once in a blue moon and the motorcycles perhaps 1 out of every 6 sale missions(its random, you might even get 3 boxville sales in a row...) the prospect is low.
All of the above is why I don't chase the $/min stuff, because it is all great theory based upon exacting parameters that rarely occur in practice. How many times are you finished sourcing a car, to walk into your bunker right as the number clicks over from $133k to $140k on the display? Probably almost never. Given the choice, my bunker will surely sit an extra 10 minutes while I finish a source/sell mission because the bunker certainly couldn't earn me(and correspondingly couldn't lose me by not doing) $75k in those 10 minutes. And that is my point; in practice the numbers can vary and you have to adapt and constantly adjust your activities based upon what is available at the time. I often resupply, source/sell a car, source another, then do Hostile and sell a Sentinel in the cooldown before doing another source/sell. Sometimes the Titan spawns on top of me blowing up my Buzzard when I'm picking up the Hostile Takeover package at LSIA and I have to walk across the tarmac to steal another vehicle, turning my 1.5 minute Hostile mission into a 5-6 minute project. This could mean that now the cooldown has ended and I skip right to another source/sell rather than sell my Sentinel because $75k>$15k. Now that means I made $15k less that hour. A couple of these mishaps occur in a 3 hour cycle and boom, you made $50k less than you planned, or worse if it means selling even one fewer I/E car in the cycle. That turns your hypothetical $200k/hr into $175k/hr, with nothing more than your luck providing you with the police chase I/E source mission....
Which brings to my overall point. There are many variables. As you'll notice, if you can hit the marks described above every single hour for 3 hours, you will actually average over $230k per hour. Being that I'd wager probably less than 5% of folks can nail that grind every hour, and that 🤬 happens like getting that police chase source mission(and in my case simply finding new session, which also takes up time....) and the fact the despite these ideal numbers you do incur deaths, ammunition costs, pegasus costs, damage to I/E vehicles, raids, etc I'd imagine that most people are actually earning less than that.
So, in conclusion of another long and drawling post; it's not about the $/min that a particular activity earns not only because the same activity(I/E source/sell, biker/bunker sell) rarely takes the same amount of time to complete each time(again, does the 5 stop Insurgent take the same amount of time as the Phantom Wedge sale, or the police chase source the same as the photo clue source mission?) but rather about the $/min of your actual effort. From this perspective, the bunker nets me $187.5k for what amounts to less than 20 minutes of actual effort most of the time. The biker factory earns me $135k for about the same amount of time. I/E nets me ~ $75k for 10 minutes or so. Hostile nets me $15k for less than 1.5 minutes. Selling a Sentinel nets me $15-17k for 1.5 minutes or so. Not everyone has a Buzzard/Hydra at the ready to do Hostile so quickly, nor does everyone have a garage full of Sentinels to sell at all times, and some people are just more comfortable doing other activities or just simply enjoy certain missions. There are also various 'tricks' or alterations to the previously detailed grinds that I employ to increase net gains, and the above is just a more general scenario. As such, I expect if you ask 5 people for their grind routines that you may find 5 very different processes. Diff'rent Strokes.
Now, if your grind consists solely of a single business or bunker alone, with no other activities and as such you spend your time sitting round waiting for that one business to fill; then the $/min becomes relevant. However, that shouldn't be your process. As illustrated, to capitalise upon your income earning ability you must incorporate several different activities at once. Running a bunker and biker business, doing the hostile takeover that is 30 seconds from your warehouse on the way back to your office, selling a sentinel every 48 minutes on the way between two activities, resupplying as you begin a sale mission, etc are all necessary to hit these targets consistently. This process is largely agnostic to the time to mature of the various businesses, and instead treats those sales more like a 'bonus' to your already existing grind. While this is not in disagreement with anything that anyone has posted here and should not be taken as such, it is taking a different perspective to your grind.
My usual disclaimer of late; I haven't tested the bunker today so I am basing the 'new' data on what has been reported here, and as always the numbers above represent a solo grind. I am not attempting to force anyone's hand as to what activities to engage in, but simply illustrate what my process is in the event some assistance or insight can be had from it. As reiterated perhaps several times to avoid any confusions like in the past, these numbers are always assuming the best case scenario(which is odd because it's still more conservative than most others you find and yet still more liberal than most find in practice) and don't take into account those items such as deaths, ammunition, pegasus vehicles, raids, bounties, clowns, the Ferris Whale, rain, R* traffic, UFOs, how many ales you've had, how many your neighbour had, nor the phase of the moon. Please also note that this is not the only method, and should not be inferred as such. There are many options for how you play this game, and while even the grind above can be improved upon(as detailed with various tricks and alterations,) I am a lazy player. This is a video game and I don't tend to turn on the PS4 to go to 'work' but rather relax. My grind method, when done properly and all goes to plan; usually results in just topping that $200k/hr. Where I probably differ from some others is that I do so whilst really only spending 35-45 minutes of the hour active. Folks familiar will recognise this from my penchant for spending hours idle in my apartment, just to emerge for 30 minutes to make over $400k in that time(yep, I can; and I do) only to sink back into the depths of my yacht or drink beers on a bluff for another couple of hours. When you learn where and what to prioritise it is possible to best that 3 hour average and not actually be 'working' for probably 1/4 to 1/3 of that time. To do so you must use be resourceful as in identifying where to stuff in an extra activity, using your hydra to travel, running Piracy Prevention for those 10 mins you need a smoke break, etc.
For further reading feel free to find relevant the various relationships of loss ratios to combined ratios.