Stayclean,
I can see what you're doing but I don't know why you're doing it. You are making so much extra hard work putting on the multi-finish the way you are,especially on a ceiling. It would even be a challenge for a "pro" to do it the way you're doing it.....Multi finish is normally applied in two coats, one straight after the other,that way you will get very little suction. Not one coat one day ,another coat the next, and another coat the next.

That is what's making it "dry rather fast"...... Try it this way..... Once you have the pva on and it's tacky, put on a coat of multi finish over the whole wall/ceiling,(1st coat). Once that coat is on, go back to the beginning of the wall/ceiling, and put another coat on right away,(2nd coat), then you will have a better chance to finish the plaster to a reasonable standard without pulling your arm out of joint.
Roughcaster.