Playing the score
In a backgammon match it does not matter how easily you win your match, or how easily you lose it. The only thing that matters is to win it. So if the match is up to 7 points, it's of no importance whether the score is 7-6 or 7-0.
Watching the score is absolutely crucial. Let us assume to start with that the Crawford game (the one in which you can't double) has been played. So you can double whenever you like in the normal way. The match is up to nine points. You are losing 8-7. Black starts the next game with a 3-1, and you have to decide what to do next. You must double him straight away! Does it seem odd to double Black when he has started with the best throw he could possibly get? The point is that you have absolutely nothing to lose and everything to gain. He will accept, of course. But if he now wins you are no worse off, having lost two points, than you would be having lost one point. Either way you lose the match. But if you do manage to win a single game, you will have won the match instead of the score being 8-all.
It's not only when the score is 8-7 that you should automatically double your opponent. You should double him, whatever your score, whenever he is within 1 point of the match. At no risk to yourself you are making sure that, if you win the game at all, you win twice the number of points you would have.
This is completely clear-cut. But there are many other situations where the score should affect your doubling strategy, even though the situation is not as simple as this. Suppose that in a match up to 11 you are losing 8-0. If you simply play conservatively, taking no risks, and being slow to double, it is very unlikely that you will win. You would have to be extremely lucky, for instance, to win a single games before Black won three. So you must be much more aggressive than usual about doubling. It's true this may result in your losing the whole match quickly, but you were likely well on the way to a loss anyway. For the same reason, if you are the one far ahead, you should be slower than usual to double (certainly leading 8-0 you only double with almost a 100 percent lock) and slower than usual to accept doubles. Why take risks?