Sometimes, as chams get older, they dont need to shed each body part.
SO they may just shed a foot, arm, leg, etc. when they need to.
If there is no obvious sign of shedding, its normal.
If there is skin obviously shedding, then raising humidity and extra long warm water mistings will help.
SOmetimes, tiny pieces of skin just wont come off, but its ok. So long as it doesnt cut circulation off to a body part.
THis doesnt happen often. IF it does, we suggest long warm showers, and if it still wont come off, taking a q tip and putting some mineral oil on the piece of skin to help remove it.
FOr the most part though, we just let them be.