I was reminded of this by something I’m working on where there is often a flurry of short notes in a bar that is otherwise metrically straightforward.
I would probably prefer an 8th-note symbol under just the tuplet rather than the quarter not under the whole beat. Reading a score full of this sort of thing, I don’t really want to be told how many notes there are (I can see that!) but the duration of the whole group.
Corigliano’s notation is certainly easier to read than figuring out whether “7” means “7:4”, “7:6” or “7:8” in situations where it’s not spelled out, and it’s easier to read than mentally working out the length of the tuplet even when the notation explicitly says “7:something”.