I don’t know how many times I’ve been in gun shops or sporting good stores where I picked up a new or used rifle and noticed the reticles were not level. I can see how if you are working at Dick’s sporting goods and a sales clerk is told to put a scope a rifle he might just throw it on, but every year I am on a firing range during October-November, I see a large group of hunters show up shooting paper plates with groups that I would consider terrible and they go home thinking it’s good enough. Well it might be for a 100yd shot, but it’s an almost definite miss at 200yds and if you know your rifle optic is level, it’s all science and knowledge of ballistics that will make it a hit at 200yds. If you have a range finder and mark of territory when getting into a hunting position, just about any 30 caliber hunting rifle from 30/30 level action to a pump 30/06 can be effective well beyond 100yds.
I’ve done a lot of target shooting just using hold overs and in the real world this is probable a very effective way to learn to hunt and shoot instead of having to dial in MOA clicks which can cause you to lose out in an opportunity. Having a good cheek weld have proper height scope rings can also have an impact on being able to quickly acquire a target. I’ve never been a fan of large see through scope rings because in my humble opinion it can through off the balance of the rifle. I mostly see that on lever actions but if it works for you, that’s your decision. If you don’t have a level then just find an open area of your home, lay your rifle down on pillows and find a table or flat surface that you can align your horizontal crosshairs on your rifle scopes to. This is how I’ve done most of my leveling and I’ve done well at 600yds without windage issues when I had to make scope turret adjustments.