@Okie_Poke @onlybrowning both good points--of course your zero may shift if you change components or something else changes. Your specific questions and points have been addressed dozens of times before in other threads, because "this thread" comes up about monthly, and has for many years.
If I say my zero hasn't shifted, I mean it hasnt shifted when
no changes were made. Atmospherics does not measurably change a 100-yard zero. I expect that my zero at home at 1000' above sea level in the east, is the same as it is after a flight to colorado when I verify zero at 7 or 8 or 9,000'--the actual shift at 100 yards is less than 1 click on a scope, so this is a not something that realistically qualifies as a change. I generally zero from prone, which I can duplicate anywhere I shoot. I know what size cone my gun shoots into so zero-checks just need to fall inside that size circle from POA. I use minimum 10-rounds to determine center of group for zeroing, I buy ammo usually several flats at a time from the same lot, I use a LRF to verify actual range, etc. I hunt with different ammo than I practice with, so when I re-zero with hunting ammo in september I dont count that--that's an intentional change that I expect will cause a small shift in POI. But I DO check zero again in January after hunting season to verify it hasnt shifted, then re-zero with practice ammo and I verify zero every range trip thereafter. I record everything in a notebook that lives in my shooting bag, so I have a running tally of zero-checks, about a dozen and a half per rifle per year, so it's pretty easy to go back and check or track a minor issue.
If my zero is off or groups open up, I am checking witness marks on action and scope mounts to see if anything loosened, checking barrel float, etc and double-checking zero to verify it isnt me. After that I can swap in a spare scope that has been good in the past. I think a lot of times it's the action moving in the stock or the scope slipping in the rings, a self drop test can help to identify some of this sort of thing before it happens in the field--it's really proofing your entire gun setup, not just the scope itself.
This has all been covered in the scope eval threads as far as the
scope eval methodology and what it is testing, how to verify that its the scope and not the rifle, etc. Also some info on on how to set up a rifle to prevent issues inthe first place, and then if you do have a problem how to isolate where the problem is and then correct it without chasing your tail.
This podcast episode encapsulates much of that info in a fairly condensed place.
For sure I had a learning curve when I had issues with wandering zero. The problems I was having, and the tools to troubleshoot, diagnose and fix, are actually how I found rokslide in the first place. It took some convincing, but when I started using different scopes, with more intention put into mounting and setup, the problems stopped happening. There are always people raising straw man arguments that have been addressed before, gaslighting those that have experienced issues and those that havent, extrapolating their own experiences onto those with different experiences (in both directions)...all I can do is relate
my personal experience. But I will say when swapping out scopes back and forth literally opens and closes groups, it is clear as night and day when the scope itself is the only variable causing those problems to happen. At that point it's fair to say "it's the scope, dummy". Before that point, yes, there's a host of other issues that need to get addressed first to isolate the scope as the problem--it's just that it's pretty easy to address those ahead of time so they are largely eliminated, and relatively easy to identify if they do happen.