I’d been making similar calculations, based on the feeling that if you’re now giving them (admittedly rather slow) twenty ton rubble lorries they’d surely find a way to use them to their advantage.

On the other hand, I wouldn’t have thought the lorries could be seen as replacing such an inefficient use of labour as single workers carrying 50 lb baskets. Labour may not have been all that cheap and plentiful, and this may have pushed them to find more efficient means of moving baskets (dragging along greased trackways etc) so each workers productivity was much higher. Rubble is infinitely divisible, so you’d naturally find the optimum volume for handling it, perhaps also dependant on the distance and gradient, so there may have been multiple solutions. Sarsens on the other hand are indivisible and if there’s a particular super-efficient method available then that’s what you’d go for.

So I take your point absolutely, FW, that if Gordon’s system implies we should downsize the numbers involved in construction then this would be most applicable to the smaller monuments. This thought is echoed in an article in British Archaeology titled “MegalithicTombs Built by Small Teams” http://www.britarch.ac.uk/ba/ba20/ba20news.html
The article seems to confirm the labour efficiency of using Gordon’s levers to raise stones and that building small tombs could have been family affairs, but the poor bloke misses Gordon’s golden shaft of inspiration about what happens if you move the lever sideways! And Aubrey Burl was standing there watching! What a missed opportunity!
Such is the fickle nature of fame.