I believe in testing broadhead flight out to my maximum rang I would shoot at an animal. I generally don't have to tune for broadheads because my bow is tuned good prior to shooting broadheads.
I think it depends on your level of shooting.
If your proficient at distance use that.
Myself i don't normally take shots further than 50 so I BH tune at 20 to get close and verify mine at 50. If its all good to go I'm done.