I think this depends on what the fabric is. Themes like 1930s, I usually only buy 1 yard. Novelties, I usually buy 1-2 yards. If it looks like it could be a focus fabric, I usually buy 2-3 yards. If it's something I would use for a quilt border, I buy 3.5 yards since I usually make queen or king size quilts. For blenders, tone on tone, shirtings,solids etc. I would buy 2 yards. For a binding fabric-1 yard. This was really confusing for me too when I first started because I had no idea how much fabric it took for everything.