The last thing I do before I release the shutter is to quickly glance around all 4 edges of the framed image to check that there are no annoying intrusions that may be difficult to deal with in the darkroom.

On the subject of using a square format and always printing the full frame: why place such a restriction on how you "see" a subject? I think you are in serious danger of making photographs to a formula by following this practice, square prints do work but not for every photograph you make. I've taught myself to frame the subject before I look through the camera and so eliminate the possibility that I'll frame to suit the format.