The Bosch Platinum Plugs have been in our 06 Burb for 52000mi+.
What is important, (you've already learned?). Is to remove them every 10k or so, wire brush the threads, wipe with Brakleen and coat the inside of the boots with dielectric grease. Its not unusual for todays quality plugs to last 5yrs or more. BUT, when it is time to replace, it helps if you can get them out.
Handy to have in the traveling tool kit...
"Sticks & stones can break your bones...and hail will dent your Airstream"
So when is this..."old enough to know better" supposed to kick in?