Hi.
I've been thinking about posting for a long time, and your question made me come out of my shell. My husband (DH) travels often. He says in general, the mid/size to small airports seem to take the longest for security, especially if they are checking cars. Most of the major airports have the system down pretty good, with the except of LAX which he hates. But his advice, when in doubt, call the airport and see what they recommend. If he isn't sure, he allows two hours and he hasn't missed a flight yet, but in some smaller airports he has come close.