^Typically a mutant's powers are a natural function of their body so they would probably mostly be dependent on their general health, fitness and nutrition. However, we've pretty much already agreed that the regrowth from a few cells idea is patently ridiculous.
Every time he took a shower the skin cells he washed off would grow in to new Wolverines.
Every time he took a shower the skin cells he washed off would grow in to new Wolverines.