Normally, we say aim for a CYA level of 30. I'm in NJ, so I like to have CYA around 30 for the first half of the season then bump it to 50 for the latter half, when it's really oppressively hot. I adjust my FC level accordingly.
aylad (Janet), down in Louisiana, keeps her CYA at 70-80 and her FC in the 5-10ppm range. Otherwise, at lower CYA levels, she's adding chlorine once or twice a day. Me, up here, I'm adding it every other day at most, usually less.

Carl