I did a quilt where I had one pieced block next to one fussy cut block throughout. The pieced block turned out at 5 inches unfinished. Then I fussy cut all 86 of the rest of the blocks at 4 1/2" each. Of course I used so much of the fabric that cutting it again was impossible. I was so mad at myself that I left the quilt unfinished for almost a year. Then I pulled it out and carefully put a thin border on each one of those 86 fussy cut blocks in order to make them into 5" square unfinished. I used a dark turquoise blue for these borders, on all 86 blocks -- ugg! -- it took forever. But the resulting block now has a "frame" that really "pops" the turquoise in all of the blocks, and the ultimate result was stunning and unique! Now I love the quilt.
The point is, you can look a what you did as a mistake, or an opportunity. It's entirely up to you.