[Blackthorne]

"NiCd batteries, when not used regularly, tend to develop dendrites (thin, conductive crystals), causing internal short circuits and premature battery failure, long before the 800-1000 charge/discharge cycles claimed by most vendors. Sometimes, these dendrites can be cleared by applying a brief, high-current charging pulse to individual cells, but once dendrites have begun to form, they will typically recur soon thereafter."

AND

"In the old days (ie. 80's, 90's) when NiCADs were more common, it wasn't uncommon for a cell to fail prematurely due to the electrolyte deforming enough to allow the anode and cathode to make direct contact. Especially common as the cell got older or if it was abused during charged / discharge. This would cause a dead short, the cell would go to 0V and never accept a charge. "Zapping" meant taking a higher-voltage source capable of a large amount of current like a car battery and for an instant placing that voltage across the terminals of the failed NiCAD. If you were lucky, the bridge between the anode and cathode would melt or vaporize and the cell could be charged and used again. If you were unlucky, the cell would become incredibly hot, vent, catch fire, something like that. I remember bringing back a 12V, 7000mAH NiCAD that had failed this way, by locating the failed cell and zapping it with 12V.

When people talk about zapping, they're talking about the same type of thing, only done to perfectly good batteries in an attempt to increase the actual voltage. Abusing the cells like that only shortens the life of the cells. Unless the cells are poorly manufactured to begin with and have bridges or near-bridges across the electrolyte, or some kind of impurities, it won't really help."

I'd have to agree with you on the "matched" . I would guess the battereis are tested and those detailed recorded, and then their characteristics are compared and matched for uniformity.