I charge the same, £1 per window. Im not slow either.
Over the years Ive employed at least 20 experienced window cleaners from other companys and to be fair most of them are not as quick as me.
It seems to me that there is a lot of window cleaners setting up in the area at the moment, hence it being very competitive.
Quoted a job the other day, just the fronts & sides (building work going off at the back), on the ground there was a porch way 3 sides to it, 1 bay window, 2 small windows down the side, on the 1st floor there was 1 bay window & a small window. Quoted £8.00, lady said no chance I paid £6.00 for the whole house. How can you compete with that, you carnt, well I carnt.