I can see plenty of situations neither advice nor feedback is really warranted. I know that in my own case, I'm often aware when I've made a mistake, and I'm working on correcting it. Call me a slow learner, but there's often quite a noticeable gap between the time when I can detect a problem and when I can correct it. When I'm in that gap, I don't really need some self-appointed quality control manager telling me about it.
In my case, I often find that the problem actually began well before it manifested itself in something that uke could feel. My timing was off, or an entry angle was off, and so the technique I intended was *never* going to work. But uke didn't realize it until the end, where I ran into his structure or whatever. So his advice, no matter how intended, simply isn't going to address the problem I was actually having and in fact distracts from whatever I'm trying to work through.