What is important is that you have your reticle pointing at the exact center of your bore, and that your reticle is level when you shoot. I described how I make sure the reticle is lined up with the bore in the thread linked below. I use a scope level when shooting to make sure my reticle is level.
My rifles shoot perfect (no left or right change) at 100 yds and 1,000 yds and everywhere in between. My permanent scope level is not cheap but the only things I need to
mount a scope straight are a home-made plumb-bob and some (free) paper targets I print out myself.
People will tell you about how great their device or system is when they never shoot at 600 yds or more and therefore have no clue how straight their scope is. Or they'll say, "Yeah, my POI shifts as I increase range but that is due to 'spin-drift.'"
No, they just don't have their scope on straight.
There are two parts. First, you gotta get your scope mounted so that the reticle points at the exact center of the bore. I'll take trial and error over a gadget for this any day. The "tall target test" takes only a half hour and lets you know for sure.
Second, you have to
hold your scope level when you shoot. That is what the permanent scope level is for. You will not find a single serious long-range shooter trying to shoot at LR without a scope level in place. They know that without something to tell you when your scope is level, it will not be, and your POI will be off accordingly.
If after your scope is mounted straight to the bore and it is level you don't like how the stock fits your hand or shoulder, you have to get a different stock. You cannot loosen the scope rings and rotate your scope to solve the fit problem or else you will be feet off at 1,000 yards.
https://www.longrangehunting.com/threads/what-do-you-use-to-level-the-reticle.232353/