AZ
Yours is a "Counsel for Perfection" -
nothing wrong with that at all ... but 
-) ) Show me a perfectly straight barrel ('BNIB' or unused) -
it wont be perfectly straight, then show me that same barrel on a very cold day after 3-4 thousand rounds have been thro' it + a bit of general owner knockabout !
I cannot speak for 'Kris' here but I think we are on the same script...
approx.
Here's my methodology -
MOUNTS I choose good mounts/rings -
I distrust those that clamp from one side (& also have 2 diff. sized clamp options). A pretty good test of any rings is to run your finger around the inner surface of the rings when they are tightened ('hand tight') off the gun. Many times you can feel a ridge between the upper & lower sections (& the Mk1 Human Finger is capable of
extremely fine judgements, folks!), this tells you they are not matched or machined from one piece, then matched - you could try turning the top section or swapping with the other set, most likely it wont improve matters. SO, what to do?
Buy a set of good quality mounts in the first place - BKL get my vote but there are others (some PB rings clamp vertically).
The reason for all this is have the best possible vertical alignment of Barrel, Rifle and Scope
SCOPE I favour a brand of mid-market Euro scopes, before they go on a rifle I optically centre them
(using the mirror technique or sometimes the click method).
Using a bubble level and a plumbline I do my best to have the scope sitting correctly in the mount cradles before tightening down (diagonal bolts etc).
Now mounted into the rings I use an optical boresighter (largely out of interest, they are not essential) - I fully expect to see small variations which equate to around 1-3 "clicks" in both Windage & Elevation from scope to scope. I also do a 'dry run' Box Test using the boresighter, if OK, I then properly establish the Zero by actual firing
(remember that !) When the usual further adjustments are made to bring the Reticle to the Point of Impact I reset the Turrets
or make a note of the settings. Then I SHOOT the Box Test.
If all OK -
I'm done & dusted !!! (at least for a short while, monthly Zero checks are advisable). In my view a lot can be put down to "BELIEF" in your setup, if you lack confidence in 1 area (of equipment) then ...