This is probably not best practice, but I set up a “charging station” in my workshop and in my office for my 20VMax, Flexvolt, and M12 batteries. It’s just a shelf. I put discharged or partially charged batts on the left. The charger is in the middle. Charged batteries on the right. When I need a battery I grab one from the right-hand side. When I’m done using a battery I put on the left side. Whenever I happen to be walking by the charger and I see that it’s finished charging, I take the charged batt and put it on the right-hand charged side. If there’s any discharged batts on the left then they go on the charger. This means I end up keeping some batts fully charged, and often times batteries get left on the charger overnight if not for days. I have not had any issues with any of my batteries failing prematurely. I’m still using some of my Dewalt 20V 5ah packs from 2013 and they have all been handled this way, the only batteries I’ve had to replace have been from physical damage (cracked housing).
I have a family member who does a lot of gardening and uses the Ryobi 18v system. They keep their charger in the garden shed which has no insulation, AC or heat, and it gets mighty hot in there during the Texas summer. They keep one battery in the charger and the other, charged, sitting right next to it. They’ve been using those same batteries for 5 years now and they’re still working fine.
In my experience modern power tool batteries are remarkably tolerant of abuse and I wouldn’t overthink things. We’ve come a long way since the Ni-Cd days, benjamenjohnson is correct that modern chargers auto-shut-off when the batteries are charged.