I handle my BP lots, maybe every to every other day for around 15-20 minutes(it depends.) He doesn't get stressed, but after a while does start to get kind of wiggly and that's when I figure that he's had enough and he is put back. You just have to monitor how her behavior is; some snakes don't mind being handled one bit and are very calm, while with others, you should be ready to donate blood.

Just make sure not to handle while she's "blue"(eyes fogged up due to impending shed,) and wait 48 hours after feeding to handle.