Hey guys recently installed (4) new 1/2" sheets of drywall on my friend's mother ceiling and bedded, taped, second and third coat mudded the seams primed and 2 coats of paint and the drywall seams are still somewhat visible...if you asked her mother it is like the sky is falling and she is...
I have been a big proponent of Durabond for skim coating, plaster repair, and a variety of applications. Specifically, my MO is usually:
1) Oil Prime, or otherwise stabilize
2) First Coat with Durabond 90
3) Second Coat with EZ Sand 45
4) Sand with 9" drywall sander
5) Final pass / touch up...