I'd been told by a competitor on the show that timing the button press correctly was an underappreciated part of the game. If you press the button before you're

I'd been told by a competitor on the show that timing the button press correctly was an underappreciated part of the game. If you press the button before you're allowed to (before Mr. Trebek finishes reading the question) your button is locked out for long enough (maybe a second?) that you're unlikely to get a second chance at that question. So I assume Watson wouldn't be allowed to "spam" the button.