Does each submesh have it's own limits on vertices?

Does each submesh have it’s own individual limit of 64K vertices or is the vertex limit constrained to the amount of vertices currently in the “parent” mesh?

This author – Does the (over)number of vertices make conflicts with the materials? - Questions & Answers - Unity Discussions – says that the limit is for all the submeshes with various materials. And based on some testing in Unity 5, that appears indeed to be the case.

So, unfortunately if you have one mesh with two 40k submeshes, you are in pain. Like I’m in pain today. ;).