In Doom Eternal, there are many secrets and easter eggs that a player might miss when going around slaying every demon in sight. This is likely why the developers implemented a fast travel system. This system allows players to quickly go to set points on the map, ensuring that needless and boring backtracking is minimized.
To fast travel in Doom Eternal, the player must meet a few requirements first. First, the player must find the automap, located somewhere throughout each level. This will unlock the whole map to a player, even if they have not been to that part of it.
Second, the player must also be near the end of the level. At a certain point near the end of each level, the player will receive a notification informing them that fast travel is now available.
Now that fast travel is an option, the player can back to areas and explore. This allows them to look for secrets and do challenges and trials that the player missed going through the level and might have missed entirely if it wasn’t an option.