The main problem I feel with many hunters approach to this topic is they want to deal in absolutes and that is just not possible here.
Well I'm with ya there!
I'm just wondering why it can't be something AS SIMPLE as a biological trigger within them that cycles so many days after they birth. It would make sense as to why they come into estrous at differing times. They're certainly not dropping fawns on the same day.
Interesting.....and I'm convinced you've done a lot of research on this. Kudos.