I'm torn. 'No tuning' is quick and easy, and 'fair'. If it wasn't for the fact that most stock tunes are pretty poor, I'd vote for that for the dailies. On the other hand,
@praiano63 and others did a wonderful job supplying tunes during the beta - it only takes a moment to plug one in, and even less time to adapt one to a different track (perhaps not optimally, but good enough to have a good race).
I'm not sure they can add many more sport mode races. Remember the bug when the two FIA races started at the same time by mistake, where the fields got mixed up between them? That implies they can't currently have two races starting at the same time with match-making, so it's probably stuck at a maximum of 12 starts per hour. Also explains the cycle times of 20, 30, 60 minutes.
If the dailies stick to being one each of 20, 30 & 60 min cycles and there's two FIA races to fit in per hour, then at most there's space in the schedule for 4 more 60 min cycles, or 2 more 60 min with 1 more 30 min. If they want the flexibility of being able to run three 20 min cycles for the dailies, then there is only space for one more 60 min cycle race. Of course, in hours where there aren't FIA races there are more slots available, but their system might not cope with being able to use them.
This is the current schedule:
:00 - FIA Nations
:05 - Daily A
:10 - FIA Manufacturer
:15
:20 - Daily B
:25 - Daily A
:30 - Daily C
:35
:40
:45 - Daily A
:50 - Daily B
:55
Sorry for the long-winded reply, but I've been thinking for a while that there would be a fairly tight limit and your post prompted me to work out what it might be