I have been flying mostly within Europe, and have never seen this. For my flights gates are usually printed on the boarding pass and known well in advance (sometimes they do change, however). Half an hour before the gate closes seems quite impossible to me... how would anyone be able to make their flight on a decently big airport?
It's a huge pain - you have to sit in the central waiting areas, but can never really relax because you have to be alert for when your gate is available on screen.
Sometimes if it's far you'll need most of the time to get it. It's this way in London and I've definitely seen it a lot of other places in Europe too.
You know which terminal you're flying from, and I've yet to see an airport where you can't get from the central waiting area to the farthest gate in 15 minutes or less (20 if you walk slowly)
