[FrankenMauser]

The fact that you're asking these questions means you're thinking, and that puts you ahead of the average Gomer. But...
Don't over-think it.

Just hit the basics and make sure you're covered:

Know the rifle.
Know the load.
Know how to judge (or range) distances.
Be prepared. (For altitude, terrain, weather, and packing that heavy carcass out.)


Me?
I shoot what I hunt with. But I also don't shoot much of it any more, because I've been using the same stuff for years, up to decades. I know it works, so all I need to do is re-verify my capabilities and make sure the rifle hasn't gone to crap.
...But I had to dump a bit of money into bullets (I reload) for the initial load work-ups, testing, and range verification. (Like building a 'dope card'.)
The initial investment paid off in the long run.

But if I couldn't have afforded to buy Nosler Partitions to 'practice' with in the beginning, I would have turned to factory ammo for practice AND the hunt. Ten years ago, it probably would have been Remington Core-Lokt ammo.
Today, it would be Hornady American Whitetail (and then on to other stuff, if that didn't work). The American Whitetail ammo is fantastic in every rifle I've seen it tested. It may not be the 'best' that each rifle has seen, but it's good enough that myself and the owners of other rifles I've tested or seen it tested in would have absolutely no qualms with picking some up in a pinch (or as standard/general use ammo for non-reloaders).