I crop 5x4 all the time. I tend to see scenes in three different aspect ratios. Normal 5x4, 1:1.618 (the "golden ratio", about 5x3), and 1:2.5 (classic pano, about 5x2). Because of this, it's much easier and cost effective to just use the one film size and crop as needed.
Originally Posted by wilson2
Not to mention the money you save by not buying a roll film back, and the weight you save by not having to carry a roll film back around with you (especially if you backpack).