To be honest, I am not sure, there is a sweet spot for resetting.

It is too much dependent on your personal speed bonus. How much energy you have. If you do filming sessions, If you do challenges etc.

But since the game progression is near linear while you do not have to wait for money/skills, your personal sweet spot is very likely at the point where you have to wait for money/skill.

It gets more complicated, if you try to do only resets and not do 10h filming sessions. You can leave girls out, like Cherry and Geeky, and still progress. Then you could reset earlier and do later girls more often, but completing Cherry gives you access to some scenes of the next girl. And so on.

And even more complicated, if you consider warp. If you need 17 more diamonds to buy the next x8 warp and you are only a few days away from completing a girl for the first time, you might be better off just waiting and collecting the 20 diamonds for her scene#10 and getting the warp.

I once tried to guesstimate a ratio of bonus/hour to decide if it is better to reset or doing certain fake its and having access to more scenes this way. There is a relative sweet spot, if you do not do any fake its longer than 20 seconds. After that the ratio steadily but slowly grows. Of course, this assumes infinite speed bonus and only fake its would count then. But you actually have to consider the time it takes to film a scene. These will grow larger than the fake its.

So my conclusion then was to just do all scenes as long as you can fit fake its of earlier girls into the time needed to film scenes of later girls.

This is of course strategy for getting most reset bonus in shortest time. Since there is diminishing return in gaining reset bonus, you can just as well do a reset cycle of a week and benefit from more filming and practise time slots. Or resetting once a day instead of several times.