Here's another subtle technique that might be considered preventative.
At some camp it was suggested that for the throw-in 5-second count the official could start his count as if it was a hand on a clock at about the 5 and the next swing be a little higher, the next swing at the 3, the next swing at the 2 (there's a pattern here). So that if you get to the five second throw-in violation your hand is nearly straight up and you have changed your emphasis during each count - essentially stressing the impending violation.
(By the way don't count backwards or you might end up with a six second count.
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