Well, we did a shakedown last weekend in our '05 Gulfstream Yellowstone, new to us.
So we were shaking the first time the propane leak detector sounded, about 11:15pm. Went outside & turned off the propane, just in case it was detecting a leak we couldn't smell. The second time, 90 minutes later, we were cussing.
When it alerted a third time, 85 minutes after that, we covered the intake up & went back to sleep.
Our local RV place says the same thing I read here: The detectors have a service life of a certain time period, and after that they may fail in the ON position.
Aside from this, everything worked wonderfully. But I was really glad we tested our systems before we set out for the first 7 day event where we'll be using the C as housing during the competition.