When I did my IR at PAT I had a sim instructor, Steve.
He said to me: What are the tolerances?
I said: ehm +/- 50ft or so etc etc.
He said: And what are my tolerances?
I said: 0?
He said: Right. Theres a good boy. And now you fly it that way.
I passed.
Stick to what it should be: On the dot. And it is do-able.
Cheers
Arnie