it depends on the individual fabric- if I look at it and believe I could use it in dozens of projects I may buy a lot of it- 5+ yards- if I like it but really don't have any idea what I might ever do with it I may buy a fat quarter- or half a yard. if it is a good background/blender fabric I might get 2 or 3 yards. if it would make wonderful borders I get amounts in 3's...3, 6, 9 yards--because I make a lot of queen sized quilts and might need 108" of border (3yds)- that way I don't have to piece my borders. and it just depends on if I envision it being used in one quilt or dozens of quilts