Charlotte, numbers and I have an arrangement: We agree to stay as far apart from each other as possible. I guess I don't have a high instep. I decided the problem I was having was that I like my socks snug and that can result in them being too tight at the heel turn. I'm going to just go with Liat Gat's method of doing it, work to so many inches (I'll have to check the pattern) and start the increases. I will, maybe, try the formula I found but the only way I'll be able to do it is to commit to working through it step by step and seeing what happens.
I've been reading Amy Pearson McPhee and her description of product and process knitters intrigues me. I knit because I love to but I have to finish something eventually to justify all those stitches. The prospect of frogging and starting over is much worse than the actual doing. Meanwhile...I'm going to try a stitch pattern I found for mitts on my socks. It's simple: Row 1: *K1, yo, k2 tog* repeat from * to *; Row 2: Knit all stitches. I'll work it on the top then incorporate it all around for the leg. At least that's my current plan.
I should never overestimate my basic arithmetic skills.