Always always always QT! When I first started I'll admit I thought the QT was a bunch of wasted time and space. I didn't do it. I got mites once and since then decided to QT. Good thing I did because about two years later I picked up a snake that had IBD and it died while in my QT, although not before infecting the other snakes I had in my QT, all in all I lost 20 ball pythons and the albino red tail that came into my QT. If I didn't keep my QT strict from the lessen I learned from the mites I once got, I would have not only lost the 20 new ball pythons I purchased, but my entire collection. Anyone who doesn't QT is an idiot, IMO. I'll QT anything that comes into my collection, regardless if I get it from craigslist or Ralph Davis.