I believe the original intent of the square format was to provide a camera that did not require one to change orientation from horizontal to verticle.
That being said, I am very stodgy and believe that I should always use a tripod except in conditions where not using one results in an improved image...mind you this is a rule for me and you should do whatever suits you. While many may not be able to visualize a b&W photo they should be able,when conditions allow the use of a tripod, to get the cropping they want unto the film irrespective of the dimensions of either the negative or paper. Good strong compostition rarely happens by chance.