It takes months for an AGM Oops I mean a good quality AGM to start to degrade in capacity. Remedy? Leave at 14,4 overnight.
When a flooded battery sulfates, standard recharge voltage does not recover it overnight. A top charge is required. Are you and your charger prepared for this?
Very abused AGMs may need recovery. The Concorde battery manual details how to do it. If you are that hard on batteries, maybe lithium is the way to go.
Massive solar always have a secondary bank undergoing complete charging. Or charging with a low speed generator. Ok let's buy a dozen 8D lithium batteries.
The true maintenance free battery costs out of reach. I have to do the best I can with what I've got. I wonder how much money 10,000 amp hours @ 24 volts lithium costs?
Anyway as far as flooded batteries are concerned, I would seriously look at Rolls & Surrette. My 31 concorde has been disconnected since the first of the year. Let's see what reality brings.