By the way, one of my favorite pastimes is to download the latex source for papers on arxiv and read all the commented-out stuff.
% we should make sure this theorem is actually true
A lot of physics journals do. Anything ending in "Letters" (e.g. Applied Physics Letters, Physical Review Letters".
Science has a word limit per article.
Nature doesn't have a hard limit, but if it exceeds 6-8 pages, it needs to be exceptional.