I never heard that either.

The way I heard it was that if you had a more uniform (spirally, corkscrew, etc) then it was curly (which can stretch or shrink by the way depending on the type of curly (some curls are just tighter/smaller/dryer than others...

But if it was more watch spring-like or wiry, it was coily which might require use of more product to achieve a uniform curl appearance...

Hope This Helps.