There are more details in this thread (which it should be noted has Mac-specific information, the card numbering feature isn’t available yet on Windows, but will be), but I’ll paste the most relevant part here:
So really the only way to do this is actually compile, and with all of the miles of logical instructions that go into doing that this of course makes compiling to get these numbers a process that takes too long to insert into many actions you’d take. Imagine having to wait fifty seconds after adding a new folder so that it can be numbered correctly. Compile may not take that long for you now, it may never for this project, but some larger projects may even take half an hour or more to fully compile—extremes aside, even a tiny 0.5 second lag would annoying almost everyone.