On 100+ hour students...
A couple of years ago, I had a student who was worrying me. To put it bluntly, he seemed to have very little in the way of either aptitude or intelligence. Wondering if it was my lack of experience that was the problem, I mentioned it to the CFI, who flew with him, and then passed him on to the school owner too. We three then had a chat. By this time, the student had about 20 hours, knew himself that he was slow, and was getting incredibly tense and making even less progress. But we three instructors agreed that he was was making SOME progress, albeit very, very slowly. Now, the two things he did have were lots of dosh and lots of determination. He also wanted to go commercial, which meant that he'd need 155 hours before he could do the CPL course. So someone had a chat to him along these lines - you're struggling, it may take you over 100 hours to get your PPL, but you ARE making progress, so does it matter since you'll need that 155 hours anyway. He agreed, relaxed, and started doing better. I'm not at the school any more, but last I heard...can't remember details, but I think he was well on his way to getting his PPL, maybe even had it. Oh, he'd also swapped from the R22 to the Schweizer, and found things much easier.
So for the really slow learners....maybe there's more than one option.