I have an inline trichlor tab feeder. I run it exclusively at the beginning of the season, i.e. with the dial set to 'full', and it takes several weeks before the CYA goes from 0 to 50. With it set this high it puts far more chlorine in the pool than necessary. My pool is ~12,500 gallons. When I set the dial do 1/4 the tabs maintain 5 ppm FC at all times, and that's with the pump running only 6 hours.

I run the feeder full blast during startup when the water is still too cold to swim. When I can measure CYA at around or near 30 ppm I add granular CYA to get to around 40 ppm and decrease the flow on the feeder to 1/8. At that point, because it's not putting enough chlorine in the water, I start adding bleach to sanitize but keep the trichlor at a very low level to maintain CYA which gets diluted from splashout and refilling.