One additional note here: If you are using a more "modern" scope which does not show cross hair movement when zeroing, you may not realize that your optics are far from being optically centered when you sight the rifle in. If its far off center you may:
Run out of travel when shooting at long range
Run out of windage adjustment under certain conditions
Have imprecise or "sticky" adjustments
Reduced clarity or other optical aberrations like "fish eye" on one side
Very slighty reduced light gathering quality
Plus some other dramas that don't come to mind immediately!
Yah, it may work OK for giggles, but its not likely to be RIGHT!
This doesn't address the issues concerning pad parallelism or other mechanical fitment dramas, BTW!