I just replaced the rear rim on my spouse's commuter after a few years of use. Front rim is still OK. From what I've read and experienced, the amount of abuse that a rim takes can be really situation dependent, as in, how much muck do you ride through? My spouse was riding a fair amount in bad weather, through construction areas where there's always mud and grit. And I'll admit that part of the problem may have been not keeping her V brakes in good adjustment. I've committed to checking the brakes on all of the bikes in the house, more frequently.

Fortunately I found a rim with exactly the same profile, and so was able to install it without buying new spokes.