A pg should notice the time and if it makes sense time wise, put your head down and drive. There's a fine line in time though because you can give the other team that same chance at a 2 for 1 or you can leave yourself not enough time with the ball. It's not as cut and dry as there's between 30 and 1:00, automatic 2 for 1. But if you do have the ball with under a minute, your best bet is to try and score between 40-45 seconds. More than that they could go 2 for 1, nullifying your rushed shot, less and you might not leave yourself enough time. Generally it's a better idea at end of first half. At the end of the game if it's within a possessions score, you don't want to waste a possession rushing something because there's no guarantee what will happen when the other team gets the ball. Plus you can always foul to assure you get the ball again if time is an issue at the end of the game.