IF you have a "smart charger" then just hook the smart charger up to the batteries after checking the water levels and forget it for the most part. You should still check the water levels periodically.
If you don't have a smart charger, then you can hook it up for 12 hrs once a month, or put a cheap lamp timer on it and it will come on for what length you select. You still need to check the water levels.
I've got smart charger s that go into maintenance mode after the batteries are fully charged, and just check the water levels monthly.
You don't "have" to disconnect anything unless you just want to.