Well rumor has it the map only takes 11 minutes to cross while sprinting... Jokes aside, unless I'm pressed for time I won't use fast travel. Half of the fun of a BGS title is finding the random events that can happen while you explore. If you fast travel you miss out on a lot of what makes BGS games so memorable.

I fast travel when I need to log out or to port the Mountain of loot back to home.

Seriously my personal head cannon already is that Vault 111 is stuffed full of Stuff I havent scraqed/sold yet and that the settlers are there to haul the stuff back and forth when I need it and to guard it

Seriously I need to hire Nodwick

I really won't know until I play the game. Most probably for the first time I'll just walk around and look at stuff. With the TES games and Fallout 3 I pretty much fast travel just to sell my loot and then I come back to where I was to walk the normal way.

I will walk to places I have not discovered.

Then I will fast travel.