Shedding is related to growth. So whilst they are growing quickly (when they are younger) they will shed more often, whereas when they get older they shed less often. Reptiles never actually stop growing (though the rate at which they grow slows significantly) so they'll never actually ever stop shedding.
Whilst healthy younger chams will complete a full shed of their skin in about a day, older ones might shed in patches, completing a full shed over a number of days.
How old is your cham? If it is still a baby (less than 3 months) about 4 weeks between sheds is normal.