Anecdotally, I’ve made it to a remote destination using Maps, then hopped back in the car an hour later (with no signal), and it couldn’t load anything. This seems to happen quite often.
Maps used to expire after 30 days (no idea why), and the auto-updating while on wifi wasn't great unless you were in the app forcing it update. Nowadays they last 365d.
Anecdotally, I’ve made it to a remote destination using Maps, then hopped back in the car an hour later (with no signal), and it couldn’t load anything. This seems to happen quite often.