Limit users at the Message step level

We need more details on this one, especially on the entry, what message(s) in each step, and what you really need to accomplish and why (the end result you are looking for).  A screenshot of your canvas with be helpful.

As described, this isn't gong to be supported directly and if this is meant to be ongoing, if there was a limit per step, eventually each step would be full, and you would run of steps if it worked as describes.

You could make this work one time with a few experiment paths.