I think this is the biggest contributor to the problem that ppl don't realize. Each player has to be in a certain spot (well, area) for the play to start. It's one of the key things that can make you run your offense really efficiently. If you can recognize where your players are, and which play that can quickly get going based on that fact, you'll rarely have issues with plays not running.
Da Czar has done a nice job of getting rid of most of the plays that break or take FOREVER to get through, but that doesn't mean you should start a play that takes 10-15 seconds to run with 15 seconds left on the shot clock. That's just bad basketball.