Changing material parameter for material instance directly on the mesh in the editor

[Deathrey (DeathreyCG)]

I was under the impression that with each modified material instance UE4 instantiates a new shader with the given parameters. Is this not the case?

No. Only if an instance uses different shader, which is the case, if you change static bool parameter or static switch parameter or overrides. In all other cases, it will be the very same shader.

Initial feature request from OP of this topic is already in the engine since 4.23 or 4.24 btw.