This is really something where there is a lot of mixed thought, my personal preference is run 24x7, which should not cost too much with a 2 speed pump on low. Basically the more you run your filter the better your water will be filtered, the question is where is overkill, and in your case I suspect you have an oversized pump already, so running on high any time your not trying to clear a swamp is probably overkill. You might even get by with running it on low 12 hours per day, I think most people would say run in the day when your having chlorine loss from the sun, but since I don't deal with that having an indoor pool I am not sure.
Ike