Oh, not that often. I probably handle a few snakes every week.
I do remember having to force myself to wait a couple days between handling Mr. Nibbles. One of the nice thing about having "many" animals is that they can all share the burden of me wanting to handle them, without any one animal getting stressed about it. I tend to play withthe friendly animals that like handling the most, of course. But I also try to handle the neurotic shy ones and the grumpy biters a couple times a month, to make sure they're at least accustomed to it. And it does seem to help.