I said this elsewhere in this thread I believe, but this only works for some jobs. If people at factories get a 40% cut in hours, that just means the factories produce roughly 40% less, etc (a lot of things you just can't do faster even if more motivated). Farms will produce 40% less food, etc.

I've billed out 40 or 50 hours on 20 hours or less of actual work time too, and it was glorious, but I don't think for a second that this would work for most non-office jobs.