Properly tiling a large heightmap?

I have not seen this mentioned anywhere, and I’m getting into the world composition tool so this is a big question for me right now.

Does anyone know for sure whether you are supposed to a tile a large heightmap with a 1 pixel overlap (so that neighboring tiles share a vertex), or do you do a regular image tile?

According to this World Machine -> UE4 guide: A new, community-hosted Unreal Engine Wiki - Announcements and Releases - Unreal Engine Forums

It’s advising use of the “Share Edge Verticies (duplicate across tiles)”, which I assume is a 1 pixel overlap between tiles. I’m not using World Machine, however, so I just want to confirm with anyone who might know for sure if this is correct.