I will stop trying to save $ without verifying that a recommended technique will work.
For example, a couple of weeks ago I purchased just enough Warm and White batting that, when sewed to a leftover piece, should have covered the quilt I was about to sandwich/quilt.
While I'd been successful zigzagging some polyester batting together, my attempts to join Warm and White pieces were disastrous. No matter how light my touch, I couldn't seem to avoid uneven bunching from time to time. And I couldn't keep the batting from stretching, creating unacceptably thin spots here and there.
Today I bit the bullet and bought new batting that will not need to be pieced.