Agreed on not overloading. Besides, having loads of players waiting outside can lead to great chances even if they clear the corner. It also depends on how many and what kind of aerial players you have. For example, one set-up I've had success with is:
Taker: Best corner taker. Also important are anticipation and technique.
Near post flick on (optional): High heading and jumping. Not necessarily a big player.
Attack Near Post: The weaker centerback. (example, Holger Badstuber)
Attack Far Post: The best aerial centerback. (example, Daniel Van Buyten)
Challenge Keeper: Good finishing, height and heading are a bonus (Example, Mario Gomez; I also had success with Gustavo)
Attack Ball From Deep: A monster of a man, high aggression, jumping, bravery, strength, heading is almost a bonus, you want this guy to power through, or at least in theory. Never managed to get more than 2-3 goals a season out of this guy from corners.
Lurk Outside Area: Whatever your best technical and mental player is who isn't already involved. High technique, long shots, passing, creativity, and decisions (example: Bastian Schweinsteiger)
The more of these roles you can assign the better. If you have someone good for all of them there's almost no point in putting someone else in the box imho. If you can honestly muster three strong aerial threats, someone with a good jump and heading, a tall finisher, and a midfield playmaker you're going to score. Lots.
Generally if you wanted to be ueber-efficient on set-pieces a 3-4-1-2 might be really good, providing three cbs (usually good aerial players), a tall forward and a poacher to play in the flick and challenge roles, and a AMC who lurks.
Has anyone here had any successful long-throw set ups? I'm playing with AC Milan testing out the TBH 4-3-1-2 and hoping to make a long-term save of it and Milan possess a lot of good aerial players and throwers.