I can do a 10 window house (including 2 doors) in 5 minutes and this is how I do it:-
0 - 1 minute Open gate knock door and clean it awaiting an answer, if custy not in write chit and put thru'.
1 - 2 minutes, go round back, look about and if no one watching check for bird's muck and if none evident ignore upstairs back 2 and run scrim along base of downstairs window and door. Wipe downstairs cills.
2 - 3 minutes, check upstairs front 2 and side upstairs and if no one watching ignore. Downstairs 2 do the scrim trick.
3 - 4 minutes. Do kitchen window properly. Head for the gate.
You now have 1 spare minute which you can use on the next house you find someone in or a nosey neighbour watching you and have to take 6 mins.
This method is only allowed Oop North, in the Welsh valleys boyo or the Gorbals in Glasgow.