A few words about fast travel. It is usually done this way - you open the map, hold your virtual finger on the icon and immediately find yourself there. This is a typical example of modern game design when the developer is afraid to cause the slightest negative emotion in the player.
After all, if there is no teleportation, then what to do? There is only one thing left - take the horse out of the pocket and hold your finger on the «forward» button. This is quite boring, so many prefer to skip the horse and immediately move on to something else. It’s a typical sandbox principle, you can throw away one toy at any time and take another. The situation when you got bored for 1 second is a tragedy. Modern developers usually try to avoid this tragedy by allowing fast travel anywhere anytime.
But I don't like it. I will try to explain why.
Almost every solution has its pros and cons. I described the pros above, but it’s not so easy to see the cons. I could say that it breaks immersion, but then it would take a long time to explain what I mean by the term immersion. Let's just say that this solution breaks the fragile illusion of a living world and turns it into a mere decoration that you can ignore.
There is another, much better, in my opinion, solution. It doesn't even need to be invented, since it was already implemented more than 20 years ago. To describe it in a couple of words, it is a symbiosis of early WoW and Dota. The system of flies between cities is taken from WoW, and teleportation to the base (to the city) is taken from Dota.
In order to return to the city you need to eat an item in your inventory (a scroll, for example). This is a one-time item and it is quite expensive. There are no restrictions on its use (you can use it in battle), but the cast lasts 15-20 seconds. During the cast, the player is vulnerable to damage. Moving between cities works like griffins in WoW - you pay money and watch the flight in real time.
With this system, your position in the world will matter and you’ll have to plan your travels in advance. You’ll look at the world map with different eyes. Instead of a menu with points of interest, you will see roads, forests, mountains, lakes. Moving around the world will become part of the gameplay and if implemented correctly, it might even be interesting.
It allows you to implement some gameplay mechanics that don’t make sense in a normal situation. For example, in DayZ the player needs to carry a bottle of water and fill it in wells. You need to know where the wells are and there is a real danger of getting lost in the forest and dying of thirst.
By the way, about «getting lost in the forest». Usually in games it is customary to show the exact location of the player on the map. But I would do it a little differently. In my version, the world map is divided into large squares (sectors). The exact position is not shown, but the sector in which the player is located is highlighted. In order to understand where you are, you need to look around and pay attention to the world around you. Having noticed several landmarks (village, lake, crossroad, etc.), you need to compare them with what is on the map and thus find out your exact position.
What’s the point in fast travel system like this? The main thing it gives is the feeling of traveling around the world. In most modern games, the world is just a dead scenery. It’s a background for dialogues and quests. Making a living world is incomparably more difficult than that. This system is just one small step in this direction.