For one a medium rat is huge for anything under 2000g IMO. Anything above Sm rat is a waste of food with ball pythons. Especially since hes only 600g, i would have him eating large wean to small rats.
I don't even have mediums in the freezer, nor have i ever fed any to my bps except for females after laying eggs to fatten them up faster.
One small rat ever 5-7 days is all they need. Keep in mind just cause they can eat it don't mean that's what they should eat.