I use a controller, so I have to have some assists on to compensate for the way I get less sensitivity in throttle and braking. But I know that I can go faster without assists.
Thanks to the dropping of Fanatec on PS4, I'm also using a controller at this stage (until I've got the GIMX), and I too am struggling with the limitations it imposes. I'm using ABS and TC, because the DS4's triggers don't exactly allow for smooth modulation (or maybe it's my fingers' fault).
The worst part about using the controller though, is the usual steering assist for controller that you can't turn off in games, whereby the game limits the steering angle depending on your speed, and even if you slam the stick left to right, the driver on the screen takes half a second to turn the wheel. This steering assist is killing my times, and making me feel like I've got very little control of the car. For this reason, my steering inputs are incredibly inaccurate, and my lap times inconsistent, so I have to be on Expert AI. Although I may need to start trying Legend with the controller, as I just won the Monaco GP from Pole in a Sauber lol.
Then why don't you do it straight away? Or does the track rubber in, making FP3 the best time to do it?
The track evolution in this game is very well done. Actually, the way track surface grip is modeled makes sims like Pcars look a bit "yesterday" in comparison. The way the ideal line on the track rubbers in over the course of a weekend, and how that affects not only grip, but also tyre wear, is handled very well. However, the really impressive part is how tyre marbles build up off line, especially in high load corners. Going slightly off line onto the marbles leads to a sharp drop off in grip, which is really cool. Trying to brake really deep, and running a little wide, can actually be a big problem, as you've got no grip on the outside of the racing line, so you have to slow considerably to make the corner.
The way the wet track surface evolves is also very impressive. The surface changes very dynamically when it starts raining, and when it stops and the track starts drying out. Racing on slicks as soon as the racing line is dry enough can be mental, because one mistake and you're off the line and onto the wet surface, and likely into a wall.
It's also nice to see they've re-modeled wet surface grip, as well as the way the cars handle kerbs, grass, and astro runoff. In 2015 the car was on rails in any condition, and throwing it over kerbs did nothing to unsettle the car's balance. This year, those things have been changed dramatically for the better. A example is at Catalunya's long turn 3, where there's a strip at the start of the runoff on the outside that's either painted green or astro-turf, and even dropping one wheel onto it will get the car out of shape and slow you down.