This is why I like 30/06
I shoot CMP surplus through my /06 through the off-season. 2-4 weeks before the season starts, I buy 2-3 boxes of the "expensive" hunting ammo, making sure it's all the same lot, and re-zero with that stuff. Might put a few more downrange with the nice stuff to stay fresh but generally don't mess with it once it's dialed in. Echoing the above, always use the exact same rounds as much as possible. I bring a backup rifle in .308, cartridges loaded with the same bullets, in the event I have a problem or doubt with my primary. Animals aren't paper - get it right the first time, every time.