These mirrored increases are very subtle. They create a distinctive line, like half of a slipped stitch. I love to use a raised increase a few stitches before the end of every row to help the selvedge hug a curve, as in the photo to the left.
This is especially effective at shoulder, hood, and hat shaping. When combined with four or more ribbed stitches at the selvedge, it is even more trim looking.
If you rearrange the stitch tension after knitting, they almost completely disappear. This is almost the only increase I use.
RLI = Right lifted increase: Lift first leg of st below the next st onto needle and knit this stitch.
LLI = Left lifted increase: Lift last leg below last knitted st onto needle and knit this stitch.
Paired SSK and K2tog will draw the fabric in to mirror the swelling effect of the paired increases.