A higher CYA level even with a proportionally higher FC level (so constant FC/CYA ratio) results in a lower absolute FC loss per day. This may be due to some CYA shielding effect in addition to its protection by binding to most of the chlorine. So if you are in a sunny area with high FC losses, then a higher CYA level can help. The main risk to a higher CYA level is if you have to shock the pool if for some reason you let the chlorine level get too low and algae started to develop. The shock level would be proportionately higher at higher CYA levels so that means you would use more chlorine. So I wouldn't go any higher than 80 ppm CYA for that reason.