Exactly right! But it has never actually been a personal concern of mine: I favor just finishing bottles that are nearly empty and not keeping lots of bottles open. Right now, I have open 5 bourbons, 3 ryes and some scotch. I agree with Bobby that bourbon seems pretty immune to changing in the bottle when the bottle, even when the bottle is almost empty. Rye likewise. But some scotches do seem to deteriorate significantly then.