How many degrees of error is allowed twisting the scope in its rings to align the vertical reticle wire plane/axis to the bore center below the scope?
Any error will cause a shift to POA if you dial or holdover.
According to those who understand the math, if you are canted 3 degrees and dial for 1000 yards with a .308, you will induce 24 inches of windage. I haven't done the calculation myself, but this seems a reputable source of information :
https://www.shootingillustrated.com/articles/2016/3/28/rifle-scope-reticle-cant/
That's 8 inches windage error per 1 degree cant at 1000 yards. Your eye can't recognise one degree reticle cant in the scope, it's too fine a measurement.
Note that if you aim scope center, and do not holdover or dial, you do not induce a windage error, so if you aim dead on, you do not need to worry about the reticle cant.
That is why the tall target test is so important for long range shooting, you can measure the distance of the holes to vertical, and calculate exactly how much cant you have. If you are unable correct it, you can at least factor it in to your data.
I'm not a fan of twisting the scope in the rings on the range to try make corrections to the tall target test, nobody can measure one or two degrees with their fingers.