First of all, if your '03 corns are eating once a week, they are probably doing just fine. That said, there seems to be quite a bit of variation in terms of feeding practices. Many of the posts you will read lean towards the "more is better" side of the issue. Many folks (especially breeders) want their snakes to grow up big and fast. This can be done by feeding the snake as much as it will accept on a regular basis. I have read many posts by seasoned herpers that suggest that this may not be the best practice for the snake in the long run.
As for YOUR snake...If it seems to want a second pink every few feedings, that would surely be fine. If it seems hungry after 5 or 6 days...no problem either (other than the fact that it is sometimes less confusing to have a weekly "feeding day" that is easier to remember!). At some point, switching from small pinks to larger ones makes sense, too. My snakes grow much slower than those of a friend of mine who grows them with the intent of breeding and selling. I suspect that this is probably closer to what happens in the wild, although I also understand that we are not dealing with wild snakes. In conclusion: It seems to be more art than science. If our snakes are feeding regularly, we should be glad (especially this time of year). Duffy