I have a (soon to be) 5-year-old Paraguayan Rainbow that sheds every 30-40 days, and that's without eating for months at a time.
I also have a (soon to be) 2-year-old Columbian Rainbow that sheds at the same intervals and that one sucks back medium rats, which is the same food size as her much larger and older friend above.
As mentioned in earlier responses, younger snakes shed more often. I recall a time when I barely got any social time with the young Columbian because she was either moulting or full, but as they get more mature, the time between sheds does tend to get longer - my Paraguayan seems to be an exception and I've made an appointment for her with a leading psycho analyst to get to the bottom of her issues of not eating and still moulting every month at her age. It wouldn't surprise me if she has Daddy issues - he was never around when she was growing-up