Why doesn't this Doom combo work?

Trying a simply X-Factor trick with Doom:

Air Plasma Beam => Air Photon Array => X-Factor => Air Plasma Beam => Air Photon Array

Simple, right? Well, it doesn’t work. After the X-Factor, you can either do a Plasma Beam or a Photon Array, but not both. What I don’t understand is why it doesn’t work. You can do it before the X-Factor, so why not after?

There is a limit on the number of special moves you can in one jump unless you are in flight.
If not you could do nutty stuff like Dorm teleport continually in the air, or any rising air special over and over and hit the top of the screen.

I seem to remember you can do a limit of three special moves during a jump. I don’t know the limit on special moves on flight, but I assume it’s two because that’s all you have time for before flight ends. But if that true, then why doesn’t this combo work with Dormammu:

Flight => Air H => L Dark Hole => Air H => L Dark Hole

Then second Dark Hole won’t come out. Why?

with doom, you have time to get three special moves out during flight mode.