How would you know if the receiver holes/rail is properly aligned without performing a light lap on them?
Every rifle application is different, but we recommend purchasing quality components. Our rings are made on some of the finest and most precise CNCs in the world. When someone laps well made rings they are trusting the lapping bar is within nominal spec, and trusting their ability to hand turn it within probably thousandths of an inch.
A good example we had is someone lapped a set of our rings for a build. Come to find out his bar was well out of spec and it would no longer hold his Tangent Theta. He was local and we were able to measure everything and confirmed the lapping bar was the issue, and we found several inconsistent low spots from hand turning it.