Sometimes in the course of one turn the game changes from a situation where your position was not good enough to give a double to one where it is too good. How can it be too good? The answer is that if you have a position where you are an overwhelming favourite to win a single game, and have a very good chance to win a gammon, then you are letting Black off the hook by doubling. For if you double, he will obviously refuse and you will only win one point. If you don't double, he has to play on to the end and will usually be gammoned and lose two points. The position in Diagram is a good example. Black should be absolutely delighted if you double him. He cannot refuse quick enough. Be greedy! Don't double.
But don't be too greedy! A lot of these situations where you have a good chance of winning a gammon can turn round and result in your losing the game altogether. In Diagram Black, with one man on the bar and two men on your one point, is in deep trouble. If he does not hit one of your men, he will probably lose a gammon. It is tempting not to double, so that you can try to get the two points for a gammon, isn't it? But don't do it. Double him straight away and take the point. Any situation where your opponent has made your one point is full of danger for you. First, he will very often get a succession of shots at you which may win the game for him. Secondly, he will often save the gammon, though perhaps not the game, by hitting you at the very end. So you will win a double game too seldom and you will lose a single game too often. Certainly he cannot accept the double, but you should be happy to take a sure point.
