Barbara Walker started the whole thing when she changed slip-one-knit-one-pass-slip-stitch-over (sl1-k1-psso) to slip-slip-knit (ssk). Did you know that most decreases can be modified in a similar way?
For example, the most common way to do a double decrease when you want the decrease to slant gently to the right is “ssk, return the stitch thus formed to the left-hand needle, then pass the next unworked stitch over the stitch just worked, then pass the just-worked stitch again to the right-hand needle.” A Walker-style modification of that decrease would be as follows. “Slip two stitches separately as if to knit. Insert the left-hand needle into both stitches together from the right and transfer them back to the left hand needle. Then knit three together.” You may find that, once learned, this is a faster way to do the stitch.
Suppose you want a double decrease gently slanting to the left? The traditional way: “slip one stitch as if to knit. Knit two together. Pass the slipped stitch over the k2-tog.” The Walkerized decrease is very similar to ssk: “Slip one knitwise. Slip two as if to k2-tog. Insert left hand needle into the front of the three slipped stitches and knit them all together.”
Instead of having three motions, one to slip an old stitch, one to pull a new stitch through, and one to pass a slipped stitch over, you now have two: slip stitches, and pull the yarn through.
Notice a pattern? The basic idea is to perform all of the slipping of stitches first, lining them up, then pull the new stitch through. Try this for a central double decrease: “Slip two as if to k2-tog, slip one knitwise, then insert l. h. needle into all 3 stitches and knit them together.”
this straightens out the two stitches so that they don’t knit crossed.
this motion is the mirror-image of “slipping two stitches as if to k2-tog,” which is used when you want to make a central two stitch decrease.