I'm in the process of finishing my basement (east-central Minnesota, US). So far, I've put up a couple of wood stud walls... non-load bearing, simple partition walls.
One one of these walls, the studs aren't exactly vertically plumb, and one in particular is about an inch out of whack between top and bottom fastening.
Note that this is in what will eventually become an inside corner of a bedroom (around a foot inward, actually), and I don't expect that I or future owners will really struggle too much to find the stud, if at all required.
How critical is the actual 16" between studs? Should I sister this stud up with another one next to it, just to make sure a mounting surface can be found in the future, or is this not a big deal?