I believe confidence is a big factor in rates of uptake and progress.
I did mine in 125 hrs over 28 years. There were a lot of huge gaps of years at a time, so there were many occasions when I had to backtrack and revise, but during the final two years I lost a lot of condidence and this was by far the biggest drawback on my progress. I began to think I was really bad and it took me an age to get from QXC to Skills Test.