The Collection feature will allow players to search by region for particular stable-masters, see connecting routes between discovered masters, and plot out which of the 150-odd stable-masters have been discovered by a given character. There’s also the option of instant travel to undiscovered masters for older content, thus ensuring that players can just quickly pick up any long-forgotten masters on the corner of the map. A recent small patch cleared up a few issues with this feature and other quality-of-life concerns, to boot; all the reason you’d need to build your own collection of places you’ve been.
Source: Stable-master Collections, Patch Notes