To Resize Connecting Rods or Not?

I just replace rod bolts and do not always resize. But I have a real dial bore gage and a setting ring gage for the bore I'm checking. I also worked in a metrology lab checking and setting up production gages. I check before and after rod bolt replacement. Like a lot of things in an engine, unless you take extreme care, how do you keep the same center to center distance when you are grinding the cap mating surfaces and then the hone? The factory stuff was pretty good from what I have seen, some rebuilders, not so much. I'll buy a virgin engine long before I'd buy a rebuilt engine. 60's and early 70's stuff is good, later stuff, seemed get cheaper and not as good.