If you have opted/promoted cleaning all frames with wfp then yes, you will have to scrub the top frame really well. Water only runs one way, down. So any spotting/contamination will come from the top. It can run in from the side frame too but as these are easier to clean it's unusual for this to cause any problems.
I personally don't clean the top frame so first cleans hardley take me any longer or give me any problems. Never had a complaint that the top frame is dirty & never had a request to clean it, I just don't mention it, the glass is perfect & that's what seems to count. However, this seems to go against what most people do as most seem to think that you MUST clean the top frame. Me? been there, done it, tried various methods/techniques etc. IMO cleaning the top frame gives way to more probs than it's worth. To achieve top results without cleaning the top frame requires specific equipment, skill & patience to perfect the method.
I'm bursting at the seems with work, get lots of good comments about my work, no bad ones. Make your own mind up.

Whatever works for you matey.