I can do some standard 3 bed semis (10 frames) in 6 minutes if the access is great and I just count the cleaning time (excluding preparation, putting stuff away and collecting). I wouldn't fancy doing it hour after hour though.
Same here shiner, but that is also WFP and not trad!
But houses vary too much, I have one bunch of houses in particular...8 of them, more or less next door to one another, 3 on one side of the road, 4 on the other and I can park the van in one spot and do the lot without having to move van.
The 3 on the one side are fairly identical houses, but the windows themselves vary as does access.
the other 4 are similar but different!...if you see what I mean, one is a little larger than it's neighbour, another has a large conservatory and georgian windows and the other also has an awkward conservatory but UPVC windows.
Worth £87 in total and done usually in about 2 maybe 2 & 1/2 hours.
so that is a potential earning rate of over £250 in 6 hours, which shows that I fully believe such things are possible.
The reality is that for the most part it doesn't work out to that at the end of the days work, other factors already mentioned creep into the equation.
But the work has to be well priced, to work trad and for one man to relentlessly bang out 5 semi's an hour for £6.00 a pop, day in and day out is I think mostly unachievable....but there was that guy sometime back on the forum that was working at that rate.
But then you stick a second guy into the mix and now you are doing 10 houses and hour, well, you might do that if you are working separately, but I don't think it is possible if you are working together, efficiency falls away.
Enough musing, I've a cricket match to cancel

So a spit load of phone calls to make...sigh
Ian