I've satisfied my own desire by starting the game all over again when companion get downed even once.
This is why I didn't reach the end for 450 hours. But I still have fun.
If you play on Tactician or Honour mode, you may very well need up to 450,000 hours of gameplay to have a high enough chance to successfully and properly complete this game (read: has to go through entire Act 3, no skipping part or all of it).
Why?
Ultimately, that's because if 2+ reasonably powerfully enemies happen to focus on the same character, this character may be killed in a single round really fast. In fact, a player character can be killed more than once in a single round.
A couple real examples from my games: I was once stricken by 2x Chain Lightning simultaneously (max damage = 160/320). By default, Karlach has the most HP among all companions. She may be considered the most durable companion. Yet in one battle, she actually got killed twice in the very first round (though also brought back to life twice during the same round). There are also potential deaths that can be caused by players mismanaging character movements or for other non-combat reasons. For example, do you know how a kiss by a mind flayer tastes like? Sweet or bitter or what?
