Running a 1/8 chain on 3/32 sprocket & chainring?

I've been running an 1/8" chain with a 21tooth 1/8" rear sprocket and a 3/32" TA 52 tooth alloy ring for some years, and I replaced the chain yesterday. I reckon about 30,000 miles from that old chain. Can't complain about that really, as I think it was lightly used when Ioriginally fitted it. Never any jumping off probllem, just spend some time making sure the chain is running straight.

30k miles? wow.
never had more than 1k miles out of an MTB chain (I run 3 in rotation). Yet to find out how long road chains (7/8spd) last.