When the Legendary Articuno came out, Niantic removed raid eggs. A while after when Ho-Oh was released (I think) they added the eggs again, before eggs was added again the Raid Timer was 2 hours (Before Battle). They added the eggs and the egg was there 1 hour and the boss 1 hour, then Niantic made the Eggs 1hour(still) and the Raid 45Minutes. But who wants them to remove the eggs again to have 2hours on the boss?
This would be very good for Raid Groups too.