I'm with Kaorte on this one. I don't have the best QT practices. I have a QT rack, but it's in my room. I have 2 pairs of tongs, and I don't wash water bowls together. When I take pictures, I'll clean the surface as best as I can to insure a clean environment, but that's as far as I can go. I don't keep them in separate rooms because I only have one room (for now). I don't change clothes when handling QT snakes. I've been dying to take group pictures of my enchi stuff while they're still young and cooperative, but I'm waiting a few weeks to ensure they're eating, and they have consistent healthy sheds. I don't have a set time.. Just when I feel comfortable (at least a month).
The things you can't see right away (RI, mites, parasites) are the things that scare me the most. I recently saw a video where the guy was pissed that he got a snake in the male that ended up having mites. He went through the tubs in his rack, and one by one, you can see each snake soaking in their water bowls... I can't imagine how that must feel.. The first mistake was placing that snake in the same rack as his other snakes...
But yeah, it's upto you man. I know tons of people don't QT. In fact, I saw a picture of a snake I sold to someone being paired with another snake, just 2 weeks after the snake was sold lol. I don't care because I know the snake was a monster feeder and was perfectly healthy, but it was that guy's choice whether to QT or not. I bet he fed the snake a few times to see him eat, then decided to go ahead and pair.