I'm afraid I use that as my motto a tad too often:
"Don't cut the yarn until the project is finished." If it's cut in the wrong place, it'll mean another knot. Especially when I'm trying to be creative and at the same time using up leftovers.
Hence the following photo (again on the plaid couch. Don't I know by now that it doesn't match ANYTHING?).
Instead of another knot, I have approx. 10 zillion knots.
Yeah, much easier.