10.5v is considered 100% discharged on a 12v battery.
Avoid taking any 12v lead acid battery this low intentionally. The exeption would be odyssey's reconditioning procedure, for when capacity has noticeably declined. They say to take battery to 10v, but under the load of headlights, which is about 15 amps. When this ~15 amp load is removed the voltage will likely rebound to 10.5v or above within 15 minutes.
http://www.odysseybattery.com/documents/ODYSSEY_Battery_Reconditioning_Charge_Procedure.pdf
Lifeline AGM are a deep cycle AGM, Top dog deep cycle AGm in my opinion, that have more than enough CCA and PCA to start an engine. But not as much as Odyssey/Northstar
They have a conditioning procedure which is different than Odyssey. it is much closer to the equalization procedure of flooded batteries. After a regular full charge, holding 14.2 to 14.4v until amps taper to 0.5% of capacity, then bump voltage upto 15.5v, for 8 hours. monitor battery temperature
http://lifelinebatteries.com/wp-content/uploads/2015/12/manual.pdf
page 20
Lifeline/Concorde is the only AGM manufacturer to recommend charge voltages this high as far as I know.
Another great read on Lead acid batteries is from Rolls Surrette:
http://www.rollsbattery.com/wp-content/uploads/manuals/Rolls_Battery_Manual.pdf
Really, maintenance and budget minded bitogers wanting their vehicle's starting batteries to last, would ensure the battery is regularly getting 100% charged, and not relying on their vehicle to accomplish this.
As far as Equalization charges, well Trojan and Rolls surrette now recommend taking the fully chrged sulfated battery to 16.2v at no more than 5 amps per 100Ah of capacity, and holding 16.2v until specific gravity no longer rises, or the battery starts getting realy hot, like 110f.
EQ charges are hard on a deep cycle battery, with its thicker less porous plates, but it will restore capacity to the maximum remaining potential capacity. On a starter battery with thinner more porous plates, well it might push a weak sulfated battery off the cliff and short a cell.
Good luck finding a plug in garage charger to get to 16.2v without exceeding 16.2, or exceeding 5 amp per 100AH capacity on the way upto 16.2v
Trojan fairly recently bumped their recommended EQ voltage from 15.5 to 16.2v.