These XR and Pint batteries are a litium NMC type cells. The charger won't overcharge and long balancing charges are required to balance the cells. I.e. balance them all to the same voltage. 72 hrs would only be required if one or more cells are badly out of balance.
I do an overnight once every 3 months and also have ZERO battery issues. Battery testing results also show that you can significantly extend the life of the battery for a battery which already has a pretty good lifespan, by not fully cycling the cells, which means don't let it go fully flat and don't fully charge them. This works for me because i have a regular commute and don't need a full charge each day.