Big chunks isn't a terribly big deal - two or three large pieces is acceptable (in my book, others may feel differently). One piece is desirable, because that means the humidity is correct, the snake is comfortable and (hopefully) all is well with the other aspects of the husbandry.

Anything more than 4 really, you may want to check on your husbandry - more specifically the humidity. I up the humidity in mine every time they go blue (Eyes turning cloudy/blueish) or go pink (their underside turns a pinkish color). It helps them much more than trying to help after the fact.

I've actually found full sheddings of garters and milksnakes in "the wild" outside of my house. (I used to live in the middle of nowhere). It's not as rare as you'd think.