As the amount of time it would take to clean the top of the frame each clean is so minimal, we clean every time therefore not giving us problems for the future.
Gazza, each property will be different, due to how much build up there is on the frames. As you clean the top frame, the dirt etc should start to run down and when you rinse it, that in turn pushes the dirt farther down the glass.Then when you are cleaning the glass, again you will be chasing the dirt downwards. Again rinsing should bring all dirt off the frames and glass. First cleans, take your time, when you have finished WFP, before you pack up, go round and check your work. You will be able to see if you have cleaned off everything. If not re-do them. A bit of extra time spent on the first clean, really does speed up the follow up maintainence cleans.