No chance :
So say you started at 8:00 and finished at 4:00pm (and thats without breaks etc)
480 mins divided by 70 houses = 6.8 mins per house including travelling and set up 
COME ON
i have a round with about 80 properties cleaned trad, i do up a lad does down, takes just over 400 done in a good day, usually i do it alone in 2 easy days 1 a week (fortnightly)
but its very compact and top windows are very low
and although the individual unit prices may seem low the hourly /daily rate adds up very well very quick
so i wont disbelieve what hes saying
what he earned although being private is another matter
ill be very impressed if the average is more than 6-7 a house!!