Good research on that talking to Rolls. Helps clarify things.
Another point on deep cycling AGMs is what member LY has reported with his. He finds it gets "tired" after some shallow cycles, and a good deep cycle smartens it right up. He see this when it starts his van better--he uses his a both starting and house batt.
That is akin to "exercising" a flooded deep cycle battery, which is in their specs to do every couple of months at least.
In my case, I don't go below 75% just to do a deep cycle. I do 50-90s while camping off grid with no solar, so I recharge starting in the Bulk stage. I leave the campground in the morning with the batts low and do the recharge to true full at home later that day.
I use those occasions to do the 20%, but first I need to keep the batts low until I get home so they will accept a Bulk stage. That is why I turn off the solar and alternator charging for that trip home.
When off grid for a few weeks on solar, it is all shallow cycling if the sunshine holds. So now you have to create a deep cycle if it can't wait till you get home.
Thanks again for getting that clarification from Rolls.