growth rates do vary per snake. What I can tell you is that in the wild a snake will eat as often as possible and as much as possible. Over the years I have seen What we now call Bush babies come into the country. Knowing that they were the same age as snakes I was feeding what I thought was an agressive schedule .( 1 appropriate size meal every 5 days) these things were almost twice the size as mine...
basically I dont think you can over feed a ball python on a once a week schedule as long as the meals are no larger than the widest part of the snakes body.