a soldier was supposed to retain more or less full combat efficiency for a period of 7-10 days on 1 1/2 to 2 hours' sleep a day
That is a load of blithers.

Multiple independent observations (including my own) is that when you go past about three days (72 hrs) on this kind of sleep cycle, judgement and quality of higher brain functions goes right out the window. The problem is that in training, most small unit field exercises are about three days, so you can usually push your people and get away with it.

Yes, I had some near misses because a group of soldiers I was leading had gotten to about four days without sleep and were still handling pyro. To this day, I am fire-breathing death on sleep discipline.