Just finished the blanket I started in October and I massively overestimated how much yarn I needed. Bought enough for what I thought would be a king size, ended up with a lap blanket and about six skeins leftover. Could not return it because I'd mixed two colors. So I figured I'd use up the scraps. Made a balaclava first as a sort of test piece, then got confident and did a whole sweater in the same granny stitch. Now I have a matching set and honestly it looks better than I expected. The trick was keeping the same color sequence on every round so everything lines up.
My husband says I look like I'm disappearing into the couch when I wear it with the blanket on my lap. Fair point, that's basially how the whole thing started. Yarn is now finally gone and my stash bin has actual space in it for the first time since spring.