I diffuse in sections using a bowl diffusor. I use high heat, low speed, unless I'm in a big hurry--then I do high speed. I do the high heat for 10 seconds and then hit the cool shot button for 10 seconds. I actually watch the second hand on the clock. If I were to airdry completely, it would take 4 hours and my roots would be flat. I usually diffuse 80% to 90% dry and airdry the rest of the way.
"For many years the National Pretend Speed Limit was fifty-five miles per hour"--Dave Barry