I am working on making 7" by 9" "squares" (really, they're rectangles) that will be sewn into a blanket later on.
Most of the patterns for these call for 35 stitches, with 1 inch per 5 stitches. I can't hit that with the asked-for needle size. I can usually knock down the stitch count easily without messing up the pattern to solve that problem. However, one of the patterns is a pain to alter stitch count on, so I knocked down needle size.
I have one rectangle going on the asked-for needle size, and I wrote down the tension I am using on it so it's smooth sailing. I have another rectangle going on the knocked-down needle size, and did not write down the tension I was using on it. It's been weeks since I picked up that rectangle. I forget the tension I was using, and might need to do a few experimental rows and rip back.