i have the best round of flaking paint anywhere (all victorian buildings)!!
therefore i use trad alot of the time . was hoping to be able to just keep the brush on the glass and clean that way but you don't get satisfactory results (messy edges, corners). so wfp is really not at all possible for flaking paint windows. the brush would also take the paint off and you get white chalking runs from the underside of the paint.
I encourage my customers to employ a decorator!!
The times you get good paintwork wfp is a dream esp on traditional leaded, georgian and the large victorian windows which you otherwise might have to go up both sides on a ladder to clean.
Ben
dunno about others except upvc which suits it to the T