As written this guy only has one monkey.

Perhaps it's in the monkey's psychology that they'd never hit the keys that much before just destroying it all. They're a pretty poor pick for a random value generator.

Not necessarily. There are an infinite number of positive numbers, but -13 will never be one of them. Ergo, even with infinite possibilities, you still may not see a particular combination (even if it does fit the criteria; my metaphor is imperfect).