Sorry to sound thick... but you mean windscreen washer jets right? Thats a brilliant idea! Will try that I think

Do you keep the brush jets as well, or just switch the tubing to the overhead jets?
m.b.s, its taken me 2 or 3 cleans to get the windows on my house perfect. I hadn't done them trad for a good 6 months, so LOADS of muck had built up in the frames, which were recessed as well which didn't help. I found they finally came clean when I squashed the brush right into the top of the frame and scrubbed from side to side, then rinsed loads, making sure the jets were angled into the seal.
Hope this helps

Chris