Unless you know how much is being fed at each meal, it is not really possible to say if the frequency is too little. I've seen generalizations like that result in a snake being fed massive meals weekly instead of more moderate meals.
In general, adult ball pythons can easily be fed every 2 or even 3 weeks. (Referring to pets, breeding animals have a higher caloric requirement and generally need more food or more often because of it.) Both of my adult males eat about 50-70g every 2 weeks and are maintaining good body condition at 1400g and 1000g.
You can feed, say, an adult male a smaller rat every week, or feed a larger rat every 2 weeks. (I.e. bottom end of a small rat weight vs the high end of the small rat weight, 45g vs 80g) It depends how large the amount fed is. Some people feed on the large side and space meals out, others prefer smaller and more frequent.
Some argument can be made based on a study of snake digestive processes that feeding too often is detrimental. Their organs enlarge in order to digest food and it increases blood flow required and puts some strain on their organs. The time it takes for their body to return to rest mode is 2 or 3 weeks, if I remember right, so when you feed weekly, it doesn't let them return to a non-digesting state. How bad this is, I don't really know. Many snakes live full life spans fed both ways, so it doesn't seem like the end of the world either way. But there are many who will prefer to feed less often and allow them to fully complete the digestive process before providing the next meal, even if it means feeding a bit bigger prey item at each meal. This isn't necessarily waiting for them to poop either. (This larger prey can be riskier for live feeding, as bigger rats are more capable of causing significant harm, but that's a keeper's individual choice as well.)
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