Every learning curve has learning plateaus. But that has nothing to do with being hopeless. We know when a student is at that stage, and work around that.
Being hopeless somebody making serious mistakes like closing the throttle completely at 100 ft on approach, after 25 hours. Going full forward on the cyclic when entering an autorotation, after having done quite a lot. I can name a whole list.
Your instructor will tell you how you are progressing. He has to keep you informed. It's impossible for a student himself to determine how his progression is. I keep student progression sheets, where I grade the student, this is done during the debriefing. So the student knows where he is at.
Hillerbee