I never make just the right number of blocks. I am always generous with the intention of using them as "seed" for another quilt.
The key word being: "intention" - - best laid plans of mice and men, don't you know <g>
ahhh, welll .... I have a lot of blocks for samplers if I ever get to them, eh? LOL <wave>
I totally buy my daddy's idea of having dinner guests: If you don't have leftovers, you have not made enough
I mean! I TOTALLY keep that in the back of my mind for whatever I am working on ;-)