It mainly depends on the amount of food you give them and partly genetics. Check out this big 5000 gram female:
https://youtu.be/P59Y771SUUM
And BHB did an experiment where they fed small prey items vs. large prey items and the snake fed the bigger rodents grew almost twice as fast, that blew me away. So I guess they will grow faster if you feed them rodents that are about 10% of their body weight vs. multiple smaller rodents that total that same weight. I feed a lot of mice to my ball pythons and I do notice that if I can get them to take a big rat they have a big growth spurt vs. multiple mice.