Lets say that I am the protaganist of a shounen manga and Luin is the villain. The story goes on for many many chapters with me getting into confrontations with Luin's lackeys and overcoming them. Then lets say we get to fight Looky, Luin's right hand man. In a to attempt make things super dramatic it is declared to be a battle to the death. One person will die, that is certain. The problem here is, that instead of making it more dramatic, it actually makes it less dramatic. Like A LOT less dramatic. The reason for that being that there is really only two possible outcomes. Either the series ends with my death, or I defeat Looky and he dies. Shounen manga are always super focused on their protagonists and there would never be a instance where that protag dies and yet the story continues. So by saying that someone is going to die you already know for a fact that it won't be me, (the protag).
Even with this seemingly obvious contradiction you still see shounen series do this kind of thing all the time.
"Echo is struggleing to overcome this trial! Will he be the one to meet his death?"
No, I won't, cuz thats not how shounen series work. I mean sure you can have something happen that changes the rules and negates the death penalty. As long as the death penalty is a thing though, its 100 percent certain that I wont lose. Plot armor I think its called. This character is important to the plot so they can never die. While that is fine and all, the problem is when you put them in a situation where they could be facing death. You ruin all tension beacuse the reader knows that there is no way the protag is going to die. Do people actually not realize this?
What would be a much more effective way of creating tension is making the stakes something like "If Echo loses this battle then he will never be allowed to flirt with large breasted women again!" This is something that would be devastating for the protag (me) and yet not a end all for the series. There could still be much more to the series if I lose and suffer those consequences. This being a far superior idea to saying If I lose I die. Because lets face it, as a shounen protaganist that jsut isn't going to happen. I have so much plot armor that my plot armor has plot armor.