Aarons post would surprise me in the pre-Pro Tools (PT) era but not in the post-PT era. My guess that would be from 1991 on.
Now, producers just open up a project and edit at will so the artistic work is dynamic to serve whatever need.
These days there's no monkeying around with the releases at all. Whatever U2 sends out is digitally sent, and if you compare a UK release to a US release and so on they are consistant all the way through with identical track timings etc.
But when labels were making the jump to CD back in the day (Canada started producing U2 CDs in 1987) each country was left to chop up and master their own CDs. It's pretty prevalent in those early CDs. On "Boy" you get "An Cat Dubh" and "Into the Heart" split differently in the US from Europe, and not split at all in Canada. And all of the tracks vary by a few seconds here or there. You can hear the differences in levels as well. Some versions are much "louder" than others.
