I like custards and they seem to leave a residue in my RTAs only after a day. I'm probably the exception, but I change my wick every other day or so and I clean my tank at the same time. I don't take it completely to bits, but I disassemble it to the major individual parts, wash each under tap water and then dry with paper towels. I'm a flavor chaser and I love vaping on clean tanks with new wicks.
After a few months when enough residue builds up on the deck underneath the coil, I remove the coil, clean the deck, and then install a new coil.