
These are faster than running, so should be even faster than fast travel. You can use Brotherhood vertibirds after clearing Fort Strong for Elder Maxson. Keep in mind that there are still fast travel options in the survival game which you can use to speed things up, even though you can't just teleport anywhere.

Not only that, but it can actually be faster to run there. Time passes in game when you fast travel. Your question is based on a false premise.
