Refractor collimation tolerances, at what point?

It is my understanding the faster the scope, the more important collimation is...but how close is close enough?
I'm particularly concerned about my old 6" F8 Jaegers because I'm seriously considering a chromacor.
With the use of a cheshire eyepiece I can get one slightly oval reflection,but not perfectly round. I'm wondering when is close, close enough?

Gary;
Thanks for the response. For my current needs I believe the scope is indeed within tolerance. The views are very sharp up to the point when chromatic aberration becomes a factor.
I hear chromacors are extremely sensitive and unforgiving about collimation errors. I will look into being sure the focuser is exactly square to the optical path. thank you, Bill

While Cheshire is an extremely useful tool, star test is the ultimate answer. I usually use Cheshire to collimate the focuser unit as good as possible, and then tweak the OG cell to get a good star test.

Dmitri