MJ
That rings very true of my experience when I did the PPL. I rarely, if ever, felt I'd actually mastered anything before rushing on to the next stage. This was particularly true of stall recoveries and even simple trimming. I found this most frustrating. Even after the skill test, I still found myself fannying around with the trim for a long time during each flight.
While I understood the concepts in the briefing, it was always hard when doing it practically in the air.
The problem with not being having the knack of trim and S&L is that you become fixated on it and your workload is significantly increased as a result. That has a knock-on effect on learning the other stuff as you're not concentrating on what you're meant to be learning. Although there is some benefit in pushing your personal limits with an instructor, if you can't comfortably do the basics reasonably well already you're wasting a lot of flying hours IMHO.