Bill wrote:

BTW, as you may have noticed from my earlier post, you helped me solve
the problem I was having near the ceiling.

My work, at the ceiling, Easysand on top of Durabond, taped, is
basically sanded vertically with 150 grit (leaving minor "striation").
So far, I've used 6" and 8" knives there creating a taper that extends
10 to 11 inches from the ceiling. I have a 12" knife for finishing. I
expect I can omit adding a layer of "All-Purpose" there and go straight
to the finishing compound (or not?).

Do you have any suggestions about the application of further compounds
and sanding (in particular, is there a worthwhile reason to switch to
strictly horizontal application and sanding)?

So far, so good! Though admittedly I've paid a high price in labor for
taking this route and not removing the drywall to the ceiling!

Bill