And I don't think you even realize what it means. It means Role-Playing Game. So if say, this FATE was done with a bunch of In-Character Role Players; Simply barreling through to the end is not what we do. If we are opposed by several crowds of mobs that seem almost endless, then we would push "in-character" as a unison until we get to the end. Think the 300 Scenario of the Spartans protecting themselves in a dome with their shields fits this case nicely. The push would be slow; but we'd eventually get there.
When In-character life or death is played as a real deal. It's like watching a Movie; the characters die if they screw up or go barreling head long into battle.