Finding the right timing?

How sensitive do you find macro timing to be. My question is when finding the right timing for a macro, is it possible to adjust the timing .005 and see a huge jump in performance. For instance you start at 2.5 the drop to 2.4, or on the quicker side from .07 to .06. Is it possible to have missed the correct timing by .005 which would have made an otherwise unplayable macro or sub performing one into a macro capable of performing in the 90% or sim.