Almost all of my batteries that have leaked, and there have been many, have been under no load. The devices had been mechanically switched off (with zero current draw), or they were not in a device. The only exception is in wall clocks, where I think the load is very small, but with repeated higher current current pulses to power the mechanical movement. In your test, maybe the load was to high, and the energy was sucked out in a few days, and there was no energy left in the battery to cause it to leak (whatever the leaking mechanism is). Also, I have batteries leak and there was still plenty of charge left in the battery, so the leakage problem is not necessarily because of being discharged.