I haven’t had that problem so far. The idea is to cut as big a piece as you can from the scrap fabric you have. At least, that’s was the goal of the quilt blogger Edel got this idea from. She has a few commonly used sizes that she cuts to. I can’t remember exactly, but I think it’s 5" strips, 5" squares, 2.5" strips, and 2.5" squares. There might be others. The goal isn’t to slice and dice all the fabric you own. If you have a fat quarter of something you love, you leave it be until you’re ready to use it. This is specifically what to do with leftovers from things you’ve already made. I know that when I buy the fabrics for a quilt, I do overbuy a little, but not by much, since fabric costs really add up.
To be honest, I found this incredibly helpful when I did it last year. Edel & I swapped quilt tops during the early days of the pandemic. We figured sending the smaller tops, rather than finished quilts, would be lighter and therefore cheaper to ship. The quilt I made for the top I made Edel called for 2.5" strips. Since I’ve done so many strip quilts, log cabins, and Irish chains in the past, I had many 2.5" leftover strips already. I pulled out all of those, then sliced up some more scraps. It felt so good to toss out the scraggly bits, and be left with ready to use strips, that I actually ended up making a whole other quilt top for myself after, and the remaining strips have been calling my name lately.