Not as often as I should. 14 tanks @ 885 gallons is hard to keep track of. I have recently started using a china marker on the glass to track water changes and parameters. I think I will start tracking filter cleaning as well. It is surprising how you can think you just did something, when actually it is overdue. I try and avoid messy foods eg earthworms, crickets, and silversides except when I am planning on doing a wc. I also try to make sure the pellets are small enough that the fish can swallow them with minimal chewing to minimize the amount that comes out of the gills. I don't think there is a one size fits all schedule. Stocking levels, feeding habits, and type and number of filters all play a role.