Are you measuring the humidity? Do you feed before shedding? Is it a spider?

I have issues if they eat a big meal. Some snakes will need 60-70% humidity for a good shed, others can do it with 50-60%. My spider has a little bit of a wobble, so she requires a little extra humidity. My pastel ate once, and shed the next day. It wasn't so good. Lol. He had a full belly, and just not enough energy.