The only times I've checked baggage in the past twenty years have been when I was traveling with either (a) an item, not luggage, that wouldn't fit in the overhead rack and had to be checked; or (b) a travel companion who couldn't fit her stuff into something she could carry on, so as long as we'd have to wait for her bag, I figured we might as well wait for mine too. (Sometimes a relationship is worth that sacrifice.) That includes trips of up to a month - and on that one, my carry-on also had to hold a bicycle helmet.