when it says to decrease by neck do you decrease going to the left only or going right also.
Both ways, sometimes you may have to decrease on a WS row.
I work mirror image decreases on each side of the neck.
I haven’t come across a pattern yet that the neck decreases weren’t always worked from the RIGHT SIDE facing. But, just in case a mirror image decrease (whether for armholes or necklines) needed a decrease from the WRONG SIDE facing, you can still execute a perfect mirror image decrease.