Roger, I bet the ones that moan are the ones you converted from trad, probably in their 70's. I have had the same mate, in fact lost quite a few to a new young trad guy.
The younger ones are OK about it, and as stated elsewhere most of them are out when their windows get done.
The newer clients are no problem either, they knew what they were going to get.
Some of those fussy old uns hate WFP, you know the ones that used to inspect every window for the slightest squeegee kick, these now have to wait until the glass dries, by which time your gone.
I am amazed by how quick people forget that their frames are being done every time, you would think they were self cleaning.
Forget about them Roger, they belong in the past.