Shedding issues in chams can be caused by a lot of different things. Here are a few main ones.
1. incorrect humidity levels/ most commonly too high.
2. Supplementation or gutload is off impacting nutrition and over all health of cham causing a slow shed.
3. Something in the overall cage set up and husbandry... Could be too dense of foliage causing major humidity pockets, misting during the day so the shed is getting wet and sticking to skin, temps too warm and the humidity too high causes the shed to not naturally let go.
4. Age of chameleon... they shed slower and in sections as they mature.