In my experience Shimano pedals last an absurdly long time. A riding buddy of mine put some 12ish-year-old 105 pedals that looked all ratty on his new bike. I asked him how he could commit such a crime. He just replied that they still worked perfectly. I believe him.
I had a pair of half-and-halfs on my mountain bike, and I wanted to get new ones after they wore out. They never wore out and I put on Crankbrothers pedals, because I wanted to try their clip-on pedals. I prefer Crankbrothers for feel, but they aren’t as put-on-and-forget as Shimano pedals are.