Well, the OP asked this question in the first place because of the assumption that 'power feeding' is bad for a snake's health.

Some of us who have been around for a while have seen the photos of 'power fed' snakes--huge, obese bodies with tiny heads that didn't grow in proportion to the length and width of the snake. Whether any of these were ball pythons, I am unsure.

I think 'power feeding' needs to be considered by species. What is true for a boa, or for a Burm, is NOT necessarily true for a ball python.

If you do not see any external indicators of unhealthy growth--ie, the snake is not obese, the snake does not have pinhead syndrome--then there is no reason to believe that there are any internal indicators, either. In other words, feeding a hatchling as much as it will eat in order to get it up to breeding size by the 2nd, or even the first, year...may not have any impact on the snake's health or longevity at all. In fact, there is no reason to think that it does.

Are you sure that underfeeding a snake, in addition to keeping it smaller, doesn't adversely effect its lifespan? We don't know that, either.