I can get on board with the big epic followed by a final 3-minute comedown track (like Luna on Siamese Dream), but overall I think the last song should be so immense that you can’t follow it with anything, such as Like Suicide (Superunknown), Only In Dreams or Mogwai Fear Satan.
The upbeat ending is a genius move if it can be pulled off though, like Show Me Mary from Catherine Wheel’s Chrome is one of my favourite last songs, just three minutes of pop optimism that make you want to whack the whole album on again.