I'm trying to imagine yearling ball pythons eating rats weekly bigger than I feed my fully mature short tails once a month. My ball pythons get smalls every few weeks. Obese snakes aren't going to produce well for you and they certainly won't live their full lifespan. You'd be far better off to slow down everything, let your animals grow up at a healthy reasonable pace instead of stuffing them with fat. Get them to 2-3 years old and judged based on the individual animal. I'd highly recommend you change their water more than weekly, I don't go more than 2-3 days max, snakes really appreciate fresh water. If you read around on here, you'll notice brand new owners wanting to be brand new breeders and jumping in huge is a big trend and most of those are out and dumping collections within a few years. It's not about you, it's about the animals and where these all end up.