Actually what is established by literature is that crunch /does/ work, but that it has disproportionate payoffs and only works on teams which already work 40 ho

Actually what is established by literature is that crunch /does/ work, but that it has disproportionate payoffs and only works on teams which already work 40 hours or less per week and haven't been recently crunching... e.g. 60 hours doesn't give you 1.5x productivity over 40, maybe 1.2x, and 80 hours is even worse return for investment... ... however it then impacts future productivity, i.e. you should take a couple of days at least after a crunch, and expect to still not be performing at peak for a couple more weeks of doing 40 hours.