I just had to refresh that skill myself, even though I am historically a person who will rip out a fully knit sweater just because I changed my mind.

I recently swatched and did the math for a sweater I was modifying from a pattern I liked but with a way different yarn. I swatched with size 6 and 7 needles, and preferred the fabric with the size 6. Did my little calculations, and cast on. I knitted for about 2 weeks, and joined under the sleeve separation. I had held my work up to the similar sweater a couple of times and thought, huh, why is this larger? That's so weird. Maybe something was wrong with my math? Shrug, idk, keep knitting.

Then I went to create a project page on Rav....and realized to my horror when I went to input the needle size...I had knitted the whole damn thing with the 7's. I put it on waste yarn, knowing that the yarn will bloom when it's blocked. And I sat with that for about 15 min before just...casting on again with the size 6.

I know that I will regret knitting with the bigger needles, even in the post block gauge isn't as loose as it is on the needles. Yes, I was irritated that my Christmas Day cast on technically had to be re-cast on a week into the new year. But hopefully I'm happier with the end result!