Don't worry, this is the last Final Fantasy boss that will be gracing the list of ridiculously long boss fights. However, it isn't far from the truth that the other FF bosses don't even touch the Pandemonium Warden.
The guy is so hard (and such a health hazard) that Square Enix was forced to not only adjust the Warden's difficulty level, but they also had to put a time limit on the battle to prevent players from overexerting themselves. So if you can't defeat the guy in two hours or less, kiss your chance of victory goodbye, as he will grow bored and leave the field of battle.
While that is unfortunate for most competitive of gamers, it is good to know that Square Enix valued the well-being of their customers over the ability of being able to boast about having an impossible-to-beat boss.