Being a developer for a railroad game, track alignment is a major thing that must be perfectly accurate. We make sure its as accurate as possible, but recently, we’ve noticed our track’s orientation shifting with a difference of about .003.
I also noticed it (probably in 2012/2013) when I was trying to make a long runway. It had a slight crown in the middle of the width of the runway (IRL this is for water drainage). In studio it was perfectly fine, but when I tested it the tiny variation of the angle from exactly 0,0,0 caused issues.
If you take the Orientation of a long Part in Studio and align it to another Part, then change the Y world axis value from 0.000 to 0.0004 (yes, 4 decimal places can be typed in!) It’ll round to 0.000 in the Properties window, but you’ll visibly see the change in orientation in the Workspace.