Personally I do not believe just because a snake eats it is hungry. This is the very reason animals in some homes, at the zoo, etc are on diets. Because many, including humans, will eat no matter what, hungry not hungry etc.
This is not to say I put them on diets. lol. I do not believe once per 4 weeks for an adult ball python is starving it. Not by far. These animals can fast for long periods of time and in some cases fast so much out of the year that 12 meals a year is not uncommon from what I hear from some keepers. Not to say you or they SHOULD do this but I do not see how it can be called "starving" or cruel.
I feed my male cornsnakes twice per month. Any more than that and I can see a noticable amount of weight coming on. Corns IMHO are very much overfed in most cases and in the wild almost every one you will find is a slender snake, not a fat one. So in that case, I only feed twice per month. Others feed their corns 4 times per month. Am I starving mine? No, just taking what I know from limited experience, reading research and others experiences and my own two eyes.
Lots of ways to do things thats fOr sure