What repeated discharging a pack to zero volts does support is that our Ni-Cd cells are nearly idiot proof. :-)

What the individual is doing is driving one cell to a much lower state of charge than the others. In doing this the charge acceptance of the cell is compromised so that on the next charge it does not reach the same state of charge as the others in the pack (unless the charge is continued for longer than the normal 14 to 16 hours). This under charged cell then is driven further into reversal on the next deep discharge and the whole process is repeated until that cell finally gives up, vents and looses capacity.

If you have ever noticed, those "experts" that persist in abusing their packs usually go by the nicknames of "Crash" or "Lucky" and are also prone to radio interference, wind shear, turbulence, sun spots, and other crash inducing phenomena totally out of their control.