Is it unhealthy for snakes to shed in pieces?

Well sort of, when a snake has a bad shed its showing signs of bad keeping and having the shed still stuck to it constantly if its shed in pieces will obviously put the snake in a bad mood especially retained eye caps!

The humidity should be a little bit higher than usual for when the snake is in shed (e.g. misting the tank daily) and some sort of rock or bark to rub against to pull it off and no handling unless it is absolutely necessary.

:-)