arse into the curve -> knee down
so this was my experience:
on my first track day, I've ridden some BMW's, S100RR, K1300R, HP2 Sport...
Lean angle was high, and I thought, my body was that much down I almost hit the street... but I did not get my knee down.
So, on year after, I booked a "lean angle course" with one of those bikes having "wings with weels"... do not know how to call them...
The instructor did a setup with this bike in a way, that we should bring the knee down even with only 40 degrees. We learned that for that angle, you'd really need to push your arse off the bike into the curve. I noticed that I was blocked on my first track day... I just did not dare to lean more into the curve.
That course was really simple and it helped me a lot to improve my driving technique.
I just noticed, that on my first trackday, I was simply wrong: the lean angle was not high enough, and my body was not moved enough into the curve... that's it.
Once you achieved it, it was not a problem anymore.
On my second track day, two weeks ago, I had my knees down often enough.
Important: do not forget to bring out the upper part of you body as well, otherwise you'll be stiffened.
So, have fun.