I guess I am a middle of the road sort of person. If it is a fat eighth or larger, or if it is a batik, or if it is a 'special' fabric, I think twice. But I just went thru my (small) scrap bin--can't face the big one right now [shudder!!]--and started by cutting enough for a hexi flower which is 2 1/2x18 or 5x9 or 6x7 1/2. Then I tried to make the most of the leftovers. I was pleased with the results even tho I only got thru about a quarter of the bin.
For those of you that cut squares, remember that you can use --for example-- 2 1/2" (for the block) and 3" (for hsts) in the same top. It opens up a whole pile of new pattern possibilities.