Much Ado About Decreases
Progress continues on my T-shirt redo. I am now back to the same point I was when I was flying back from Michigan a little over a month ago having just finished some short-row shaping for the bust. Overall, I believe it was wise to start over. I think I'll be much happier with the end result.
Here is a closeup of a pair of decreases that I did at each side for the waist shaping. These decreases are meant to be mirror images of each other, but as you can see, the ssk ends up slightly looser than the k2tog. Some knitters try to tighten the ssk up by slipping the second stitch as if to purl. This causes that stitch to twist thereby pulling in a little of the looseness. You don't notice the stitch is twisted though because it is hidden behind the first untwisted stitch. For me, the difference is negligible so I continue to slip both stitches as if to knit.
Occasionally, a pattern will instruct you to slip one, knit one, pass the slipped stitch over (sl1, k1, psso or skp). Upon close examination, you will see that this forms the exact same left-leaning decrease as the ssk. However, lifting the slipped stitch up over the next stitch causes it to stretch out a little more and look even looser than the ssk. Therefore, I always substitute a ssk for the skp maneuver whenever I happen to come across it.
Another approach is to use a looser right-leaning decrease in place of the k2tog. You can accomplish this by knitting a stitch, returning the new stitch to the left needle, passing the second stitch on the left needle over the first stitch, and then moving the first stitch on the left needle back to the right-hand needle. This places the stitches into the exact same position as a k2tog, but the extra manipulation of passing one stitch over another pulls it open more. Since the k2tog is so simple and the alternative is so complicated, I find this solution to be more trouble than it's worth bothering with.
The best mirror image for the k2tog is actually a decrease which can only be done from the purl side. You slip one stitch as if to knit, slip another stitch as if to knit, return both stitches to the left needle, and then purl them together through the back loops. Unfortunately, since these decreases usually fall one row before or after each other, you don't often get a chance to pair them up. In my case, a purl-side decrease is completely unavailable because I'm knitting in the round.