When they get so bad that they tear up your feeler gauges and give readings 010 or 015 looser than you wanted, just use a dial indicator, if you have one and save a lot of trouble. You can also sue the 1/8/turn-off-tight-method (or whatever 0.008 works out to).
I have seen them that badly worn and still in service and the owner just wanted less noise not a major machine shop job. I think those days are gone. Few are in original condition and run as daily drivers. But, I fear somebody will pipe up who has some old shop pickup that's still shagging parts, maybe with an overhead oiler too.
That's not what I did on my engine though.
