Age will have something to do with the frequency of shedding as well. A younger faster growing snake will shed more than an adult.

I had a sidewinder once who are fairly regularly during the warm months, march thru october but only shed three times in two years. I caught her as an adult, she had, i think, seven segments on her rattle.

I've had southern pacifics that shed four and five times in a single year, but they are pigs.