Kaushal's ox-hugo includes  a "Do what I mean" scope which is different
from other exporters I've seen. It goes up the heading tree looking for a
heading with the "export_file_name" property set, and exports from there,
or if it doesn't find one, from the whole file.   The code is here:
https://github.com/kaushalmodi/ox-hugo/blob/2be4bc02629bee8848f868fdfc35d9904a82d53a/ox-hugo.el#L3581

I find this feature incredibly useful, and I've copied the function to work
with ox-reveal as well.  For both of these export formats, I tend to write
iteratively, checking the appearance of the rendered document as I go.
Though it's not particularly difficult to move traverse the org-document
before calling the export dispatcher and choosing the subtree scope, it
takes some mental effort and tends to distract me from writing.  Kaushal's
code really helps me with that slight relief of mental burden.

I've just been sitting here wondering if this scope would be worth
introducing at a more basic level, so that it could be available to a wider
set of exporters.  Have other people been making use of it? What do you
think?

Thanks,
Matt