Though you should by no means delay your opponents turn more than required (I mean it... bad player, stop thinking that!), the timed turns give some units an edge. Blackbane's Ghost Raiders are a prime example, as in your turn you simply need to run them to engage, and every single roll they need to make is done in your opponents turn. You can even be gracious and let your opponent add some time to his clock if you need to take 10 free strikes and place 10 new Blackbane's, because it still doesn't take time away from your rounds. Units/models that do their thing outside your turn are great for timed tournaments.