Camera batteries - OEM or third party

CJ and I have four identical Canon cameras between us, running eight NB-2LH batteries. Clearly, we don't use more than two cameras u/w at the same time, but we may use two each topside with w/a and tele lenses (we hate swapping glass...). I've invested in eight OEM batteries which we try to use in rotation and have found them to perform significantly better than third party batteries. Inevitably the OEM batteries are sometimes just 'topped up' as opposed to being discharged and recharged. Am I doing these (expensive) OEM batteries a disservice? Should I put them under load before 'topping up' the charge? What's your take on cycling / recharging (OEM) Li-ion batteries?

LiIon batteries are supposed to be able to be topped off no problem. Probably shortens the life a little, long term, but it's not something I'd concern myself with, overly.