My numbers were just like that! Honestly!
It was all over the place initially. I kept at it and found a baseline around low 70's to mid 60's.
I kept at it even more and my numbers improved to around high-mid 80's (currently).
I need to start hitting the sims/ j/e now. I failed the first time because of the sims.
I started doing sets of 10 (because I was slow at it) then increased to sets of 30. It generally takes between 40 mins to 1 hour for me to do a set of 30 (partially because I read the explanation on the answer).
When I first started with the sets of 10, it took me about 30-45 mins to complete them.
REG-80-1X
BEC-80-1X
FAR-73-1X
FAR-75-2X
AUD-69-1x
AUD-89-2x