Fit issues: trying on socks affecting gauge for the rest of the sock?
So, I've run into an issue a few times now: if I try on a sock as I'm making it and then make the second sock without trying it on, the second one ends up too tight. At first I thought my tension was just changing between the socks since I first noticed that with long socks that took a long time, but I started doing a section of sock 1, then doing that part of sock 2, back and forth, and... it's still an issue. It's wasted so much of my time producing socks where only one fits correctly (or at all!).
This is a pair I'm making with the same yarn base, needles, and number of stitches as I've previously made two (stockinette with ribbed heel flap) pairs with; I did a bunch of trying on with the other two to try to pin down my recipe and test heel flap length, cuff length, and how much to decrease with the gusset. When I went to try it after my gusset decreases to double-check the fit, it felt too small, even though this has purling along the foot of the sock, which tends to be looser for me than my knitting, and has two extra stitches to keep it symmetrical. (I am also jumping on the broken seed stitch bandwagon; I'm using Paton's Kroy Turquoise Stripes and Muslin.)
I'd read that you're supposed to make your socks really snug to help them stay up and mitigate stretch with wear, but so far I've found they tend to "reset" when I wash them. After wearing them for a while, the stitches look distorted; they're stretched out horizontally and the sock is significantly wider and shorter than when it's just been washed. They also tend to be a bit of a pain in the ass to get on, even though they feel like they fit fine once I'm wearing them. Should I just swatch, do the math, work the whole sock before putting it on, and trust the numbers? Am I just overdoing it on how snug they're supposed to be? How do the rest of you determine whether your socks are too tight or too loose?