I dont think you need to discharge the pack after every session, if you are flying regularly. But a test of actual battery capacity every few weeks or so is reassuring. If it is 1100 mAH, it should last for 1 hour with a discharge rate of 1100 mA, or 2 hours at 550 mA. Be careful at the end of discharging as Nicds should not be fully discharged, not sure if it applies to NiMH. But all batteries have a life and it is always good to monitor their life cycle.