Game of Thrones Question

I have a question regarding Game of Thrones:

Does the Trial By Combat thing actually work in this universe? I had assumed it was just tradition to keep the people who swing swords about relatively content with however an argument ends. Then I considered it further, and it seems like every case of it ended up being decided justly.

*Tyrion just happens to have a champion at hand who can beat the knight at the Eyrie.
*The Hound defeats Beric in battle despite his fear of fire, which may seem wrong since was accused of killing Mycah, but then he was already on the path that presumably would take him to find some peace, and not many people in the Seven Kingdoms can say that.
*The Mountain seems to win his battle over Tyrion’s life… but he took a fatal blow and was clearly defeated before his last-ditch retaliation “won” the fight.

One thing that doesn’t work for me at least is that who wants to be someones second in this? I can’t see any real reason. It’s way too much to ask of someone you like. No sense to it.

Plus it never determines any right or wrong. I think it’s a dramatic device.

That last one is quite a reach, the mountain won against an opponent who was cheating.

Tyrion didn’t just happen to have a champion on hand. His plan was to call on his brother Jaime. When that failed, Bronn sized up the competition and knew he could be easily beat and did so.