To me, your current feeding schedule sounds about right... that looks like a pretty big boy, he's got enough fat reserves to keep him happy. Although take into consideration I'm generally against overweight reptiles. I've had to put a chondro on an exercise routine because she never moved and was getting to be a fatty and reproduction was nonexistant.

in that picture he was overweight because other pics, like the one on my profile of him being held he really looks overweight. those pics were from his original owner and it was that owner who made him a bit "hefty" haha. after that owner he went to a neglectful owner who didnt feed him for 2-3 months (the entire time they had him), so he lost a bit of his pudge. and now ive kept him on this strict diet. he doesnt show any signs of being underweight like his spine showing, and no sings of being overweight like spaces between his scales, etc either. so maybe he is getting enough food. i suppose time will tell....

It seems like a good ration to me as well. I would feed my adult corns a weaned to small rat every two weeks. But this was also getting them ready for breeding season. The female I had got one every week. She didn't get over weight either.

I think it's most important to use your best judgement. Everyone says to see the lump, but I think it's mostly for growing snakes and breeders. As pets, and being a snake that won't get aggressive from slightly less food, I think it's a good plan. If he slims down too much, you could go up to a jumbo mouse or a regular mouse every week.

I personally like rats, but that's just me. And I do have mice for the snakes that don't want rats. Right now though, they are sitting in my freezer because all of my snakes prefer rats. 

+1 Aaron and Andrea.

Using best judgement is a great way to go about it, and it looks like he is doing just fine on the weight situation, so one adult mouse for now seems about right. When he starts to slim down a bit, then you should consider upping him to a weaned rat or a rat pup, depending on his girth at the time. :)

Here's my way to tell. Feed him one, if he tries to eat you after that or seems to search for more right away, give him more. I feed up to 4 adult mice at a feeding for an adult corn snake. If he seems content with one, let it be.

Being opportunistic feeders, they can gorge to the point of death. I recall a study years ago of a garter snake that they fed frogs to, which it literally ate until it died. So their opportunistic feeding habits simply may not be the best gauge for them. Somewhat like humans. Put me in front of a brazilian barbeque, and I'm in a lot of pain at the end of the meal.

And I will add that my chondros will ALWAYS eat more during feeding, but I find it better to feed less, have them hunt and stretch their legs and cruise a bit.

Snakes are opportunistic feeders. they will pig out if you let him.

An adult mouse every 8-10 days for a corn your size loks appropriate. Even if there is no sizeable lump in them you're feeding them right. Once tey hit 5-6 years old they are pretty much maintenance. No need to make them larger. They'll grow how they are meant to.