GPM and turnover are basically irrelevant for pump run time.

Many pools can get by on 4 hours or less of run time but it depends on the pool and how much stuff falls into it. I run my own pool 4 hours per day and 3 of those hours are on low speed. But I would probably go shorter if my SWG could keep up.

There are 3 main reasons to run a pump.

Chlorine circulation and/or addition - For manual dosing, this can take place in 30 min/day.

Skimming - The pool surface can usually be cleared of debris in less than an hour. However, stuff keeps dropping in the pool 24/7 so it is up to you what is tolerable.

Vacuuming - If you have an automatic vac, you will need some run time but I found only about an hour per day is all I need for this.

So in reality, there isn't much to drive you to longer run times except for your own personal tolerance for debris in the pool.

Just remember that run time does not solve algae problems. Only chlorine can do that.