I consider myself to be a fairly accomplished knitter. I've successfully completed projects with stranded color work, intricate cables and lace (although not all at once). I can do intarsia and Kitchener grafting without needing to look up the instructions. And yet, there are a lot of things that I know I am doing wrong. Worse, I just can't stop doing them that way!
My secret knitting shame
This came up recently with my project that had a lot of stripes, thus a lot of color changes, thus a lot of joins and ends to weave in. There are at least four or five "right ways" to do this, including spit splice, Russian join, and the fold-back method.
But did I do any of them? No I did not. After practicing each in turn, I gave up and fell back on the way I always join yarn: I make a small, tight square knot, then weave the ends in vertically. There is so much wrong with this method, I can barely bring myself to talk about it.
However, there are a lot of things right about it, too: it's easy, for one thing. And it's secure. I virtually never have ends pop out when I weave them in vertically, because knitting tends to stretch and flex more on the horizontal axis than the vertical. However, the ends are admittedly a little more visible, if you know what you're looking for.
Tying a knot in your knitting is, we are told, never correct. According to some people it actually weakens the strength of the entire work, although I strongly dispute those physics. Knots are an affront to the aesthetics and the history of knitting. But darned if I don't just knot the yarn and move on.
I know I'm not alone in this.
This one is worse: for the longest time, whenever it called for a decrease, I would just do k2tog. Sure, the decreases weren't symmetrical. But I just didn't care. If the decrease line didn't flow with the pattern at the top of the hat, who is really going to notice? Not I, and certainly not the non-knitter who would receive it as a gift. Similarly, I only ever did kfb for an increase.
I have since decided that increases and decreases are a case where it really is worth the time to do it The Right Way. Part of the process of becoming a good knitter is learning when you can get away with "doing it the wrong way," and when you can't.