If your cleaning at fifty feet or more, it's very unlikely you will be rinsing with the brush off the glass - so does it make much difference?
Also, with a residential first clean most of us go round twice for the first clean (well i do). So what happens with a large commercial first clean ....... can't see anyone's going to do it twice?
If I want to be sure of the result at 55ft I use a technique that a lot of people use - a partial rinse off the glass. Tilt the brush head onto one edge, rinse down one section of the pane, move the brush along, continue doing so until the final section you have the edge of the brush on the edge of the frame.
For a commercial first clean that is very dirty I usually clean twice - scrub well, rinse off, do the window next to it, come back scrub again and rinse off a final time and then go on to do a second clean on the next window. Do this all the way around the building.