It's very old school, I've done both ways. Really seems to be frowned upon these days. And yes, I was "crazy" enough to do it with big constrictors. Back in day, lot of people did it. But big breeders couldn't do it practically. Because of that, I believe people figured out it didn't nessecary cause "cage aggression". For what it's worth, I no longer do it. But I still really hate when I get rodent blood and piss in my tanks. Peace.