Bendy is better
So you know that line in a lot of mitt patterns where I tell you to set aside the thumb stitches on an extra needle or a bit of spare yarn? Well if you have the option, I really recommend the bit of spare yarn. Why?
Because the yarn will be ever so much bendier than an extra needle would be. And if you try the mitt on (which you should folks, you really really should), the yarn will give you a much better idea of how it will fit than a stiff needle would.
So yes, doing it that way does mean you’ll have to find a darning needle to slip the spare yarn in there. But I promise it gives a much better idea of the fit and it’s totally worth it.