The only time that you really need to use a separate container is if you keep multiple snakes in the same enclosure, not really recommended but I've done it for short periods when I run out of space. I've also seen pet shops that keep multiple corn snakes in the same tank and separate them for feeding. I actually started with separate tubs, the problem is that you have to pick up a snake with a big mouse bulge in his belly (not good) and then try to grab him and move him when he just ate and is in feeding mode, a huge risk of getting bit. Plus I've had some really picky eaters decide not to eat after being handled, that's when I started not using tubs to feed. Plus the risk of escape with multiple snakes is higher, just more time consuming and you tend to try to rush things and end up with snakes crawling on the floor LOL.