All I can add is I've not looked up any manufacturers specs recently, however, when I was in an industry that used 100,000's of 12v
deep cycle batteries we were advised to discharge batteries to 0% and re charge prior to putting them to sleep for winter storage. The golf car industry routinely discharges and re-charges these batteries yearly and despite daily use drawing batteries well below 50% levels they come back and last 4-5 years, in most cases. My group of employees and distributors routinely maintained over 80,000 batteries yearly.
I called one of my former technicians and the industry is still doing this today. We started putting in the AGM product as an option and I'm not sure what they are doing with these, but Trojan and Interstate both got the discharge and re-charge program yearly.