The 100k workers over 20 years figures aren't a theory of modern researchers. Those estimates are from Herodotus, who was reporting on what Egyptians of his day (2,500 ybp) thought. That's why it's repeated so often. It could be that they/he was wrong.
I think it sounds plausible in terms of the amount of work. 1 man year per stone.
I think it sounds plausible in terms of the amount of work. 1 man year per stone.