I use as many as fits. For a controlled scrappy I may choose- say four colors- but there are often over 200 fabrics represented. My avatar is a good representation of what I am talking about. I mostly do scrappy - I don't have yards of anything. The little bits I have are very numerous
. The challenge is to use as many as possible for me. Also note: I have never done a string quilt or anything that truly scrappy. I prefer a controlled color palette. As I get even older - that may well change!