Experienced this for the first time on my recent Venezia cruise and didn't know about it beforehand. Towards the end the cruise, the app will begin bugging you to select a debarkation window/method. The nag doesn't seem to stop even after you make your selection though. You can choose it for everyone in your party (like when you check in for dining), which might not be the best option if your cabins are not close together.
My parents were cruising with us but were on a different deck. I wasn't sure if they would deliver all to me or split the tags between our cabins. I was stressing as I saw some folks getting tags in their mailboxes earlier (likely the priorities, but I didn't know at the time). I eventually received our tags, they were all delivered to my room and I needed to deliver the set to my parents. The tags did not come until about 6PM on the last evening.
Not expecting all this, I wasn't exactly sure how things were going to go the morning of. Without the announcements of the different #, I couldn't tell exactly when our # would be called. The app had an estimated time, but no idea if it was updated/accurate. My parents (non English speakers/readers) kept asking when we could go, not understanding we had to wait for the app to tell us. I also had to keep checking the app as I wasn't sure if it was going to give a real notification (like how dining the notifications don't always notify right away/delayed a while).
Think my parents badgering just made it all more stressful, but I think things ultimately went fine. If it were just my fiancé and I, we would of both been chill about it since we had booked a rather late train. We had plenty of time, getting off the ship faster did nothing for us as we would just need to wait at the Amtrak station.