Does that patch for popcorn ceilings that comes in a tube work well?

I have a about a 2 foot square area at the apex of my 15 foot high
cathedral ceiling, surrounding a vent. The popcorn keeps flaking away,
maybe because of moisture from the vent? I'd hate to have to repaint
the whole ceiling, since it's quite big. Also, I wonder if I should
rent a scaffold or a big ladder to do the job.

Thanks for any advice you can give.

Greg