Without actually seeing your BP & just going on your information (and no weight?), I'd have to guess that your 3' male BP IS being over-fed. I'd agree with feeding a male BP only "small" rats, and about every 10-14 days.

I agree with you that feeding him a small rat every 1-2 "months (-?- or did you mean to type "weeks"?) would be extreme- maybe they were suggesting a "diet" but in that case I'd disagree. If your adult male BP seems "underfed" on small rats, are you sure the gender IS "male"?

You might feed a small rat every 10 days for a while, & gradually lengthen the time to 2 weeks between meals. Many snakes stay in "feed mode" (ie. act hungry, as if unfed!) for hours or even a day+ after being fed. It's much like us humans, when we eat fast & our brain hasn't quite gotten the "I'm full now" signal from our stomach, so we keep eating & pack in a dessert, only to later realize we're STUFFED. Your snake is now used to feeling "stuffed", but you're doing his health no favors in the long-run by continuing to fall for his "apparent starvation".

Human or snake, our health is proven to be better when we eat enough but don't over-eat. It's not a matter of your BP being "able" to handle a medium rat- & it's not a contest. In the wild, it might even be more appropriate, but remember our pet snakes don't have the most active lifestyle- and over-eating can cause fatty liver disease or other issues that shorten his life. All this is in your control- he's not catching his prey, you're in charge of his food & his health. Sometimes food is just too much of a good thing.