John I assume you are referring to Historic Sportscar Racing? a.k.a. HSR?
And 24 Hours of Daytona sports car endurance race held annually at Daytona? i.e. the "Rolex"
Sadly I don't shoot with either the D750 (advanced enthusiast) Nikon body or their Flagship DSLR the D850.
So I can't really be authoritative with support for either.
However I do have the AF-S 200-500mm f/5.6E ED VR and out of the box it was pretty much spot on for AF accuracy (at least for my copy, yours may be different).
Something to keep in mind is the farther away from the focal plane the less influence minor off-set errors have on the capture. I'm certain you've had experience on F-Stoppers where numerous post address zone of critical focus in relationship to DOF... at distance it becomes only theoretical since it would be seriously difficult to measure.
That said, Nikon recommends doing AF fine tune at the distance you normally shoot at.
For an endurance sports car race I doubt if you would be allowed very close to the track (at least in my humble estimation). However if you actually are a credentialed event photographer you might be allowed near the "Pits" where all the maintenance action occurs. Albeit I'm thinking if you are asking this question you not quite at that level yet
Bottom Line? If your images look good, relax and enjoy... No worries k?
However if you are shooting with the vintage AF 300mm f/4 IF ED then yes I'd follow Ronnie Reagan's advice.
where he chose the Russian proverb "Doveryai, no proveryai" which literally means that a responsible person always verifies everything before committing himself to a common business with anyone, even if that anyone is totally trustworthy.
I indeed agree with this Russian proverb... Thus I test my glass before using it on a paid assignment.
Hope this helps John... and thanks for asking
All the best on your photographic journey