My '94 Silverado had what I suspect to be the OE rear shoes when I scraped it a couple years back at 210k miles.It's much easier to do nothing and ignore them.
I think I might have had then checked when I did the front brakes a few years ago and if I recall, they were fine. I need to do the fronts again, so will check them again.
What's funny is I bought shoes to replace them and never did. Will be interesting to see if they go on my '08 at some point. They are the same part number, but I'm not sure I will ever wear through the OE's. I replaced the front pads and rotors last year.