Hanging buds to dry?

A friend just harvested all twelve of his plants this evening....The question I have is weather or not you have to hang the buds to properly dry them? Can they be dried on a screen instead? What advantages does one technique have over the other?
My friend has all his buds on a double layered screen setup.....right or wrong?

I prefer to cut the plant then yank the biggest fan leaves and leftover firt (keep these for hash) then hang the plants upside down for 3-5 days.Then I remove the buds one at a time and give it a final manicure ( again keep the trim for hash).I then take the partially dried buds and lay them out on screens again in a dark room with a fan on low moving the air in the room not right on the buds. Then after 3 days on the screen if they still arnt quite ready for the cure they go into brown paper bags for 2 days getting opened once a day for 15 minutes. Then the buds should be dry and the stems should make a good loud snap if they bend they need more dry but if they sanp then they go loosely into glass jars that go to a cool dark area and get opened twice a day for 10-15 minutes for the first 7-10 days of the cure then they get closed up and put away for 20 more days.Then after the proper harvest ,dry, and cure and only then do you get to smoke.The cure is well worth the waity as the aroma when you open the jar and the clean chlorophyll taste is perfect and you ll never rush perfection again