That's not really true about spare air and hunting, when you hunt you are often alone, even if you have a buddy, there are more things that take your attention off your buddy, such as seeing a fish and going after it, pursuing it after your strike, and often in hunting you will push your air management to the limits because you have not taken any fish or perhaps you see some action toward the the end of your dive, also, you don't follow a rigid dive plan when you are hunting, because you are hunting and exploring, and you often don't know where it's going to take you, as in all things its a matter of choice, there aren't any cut and dry choices, even though a few are suggesting they have a cut and dried answer ZeN