From the SWG perspective, 100% for 4 hours vs 50% for 8 hours is the same. From a FC perspective, it shouldn't matter either as long as the FC doesn't go below the minimum recommended FC level. So if you reduce pump run time and you know FC will dip some after the pump is off, then you just need to set the FC a little higher. However, with a SWG, you should have 60-80 ppm of CYA and so the FC should not drop that much when the pump is off.

I run my pump 4 hours per day and the SWG output is set to about 95% specifically because I am trying to reduce run time as much as I can.