I think it is more of a gameplay issue than a world building issue.

Fast travel solves a problem the developers create, needing to be in specific locations regularly to accomplish specific tasks. If you don’t need to be anywhere in particular to offload collected items or to craft stuff, or return to someone to turn in quests to level, then you can just spend the time exploring at whatever pace you want.

Game design that makes repetitive travel necessary is when fast travel becomes necessary to avoid tedium.