I think the main idea is to get the batt to 100% often enough that it will return to 100% baseline when you do that overcharge. No way to know how often that is until you go too long one time and now you know!
In between you are camping and often can't get back to even close to full that day. Depends on weather and usage and how much solar you have wrt battery bank size.
Most blurbs say to do the overcharge at least once a month or even two months. OTOH they also say the best thing is to get back to full every recharge cycle. Can't do that while camping.
Once a week should be plenty to be sure you can get back to baseline SG, but not much longer with that 12v 31 or you get into a real fight to get the SG back up, like with my old 27s. Love 6s! SG comes right up with those.