[TMTTR]

In a limit game, you should never take more than 15 to 20 seconds to make a decision.

In NL, you should never take more than 10 seconds on any standard size pre-flop raise. As the rounds and the size of the bets increase, you can take a little more time but you should not go over a minute (or even approach a full minute) more than a few times per session.