The thing that screws up NiCads is leaving it plugged into the charger too long, or recharging it before all the capacity is used. Best NiCad utilization is to have two battery packs. Use one until it is discharged, and then swap it. Charge the first one and dont swap again until the second is discharged. i.e. always use full-cycles; partial cycles are bad.
NiMhs are less fussy than NiCads, but aggressive charging after only a partial discharge will screw them up, too. Most appliances use a 0.3C or higher charge rate to recharge. Charge cycle end detection relies on measuring a temperature rise in the battery pack. If you only partially discharge, and then begin a new charge cycle, the charger doesn't know that the battery is full until it get hot. The battery life is determined by how many times you heat it; not how many times it got discharged. If you start to charge, and terminate the processes before the battery gets hot, then use up some of charge, and begin charging again, that would only count as one heating cycle.