One but you need to screw him in really tight.

I think it depends on the type of monkey and the dexterity of their paws/hands/feet - whatever you want to call them. It might take a bigger monkey longer because it's harder to grip the glass of the bulb. They might squash it, and have to pick up all the broken pieces to protect their little paws/hands/feet before starting all over.

You've been tagged by the way.

Dont' bother asking a nocturnal owl monkey.  They can already see in the dark.