if a person's blood becomes desaturated (lower oxygen) because of high altitude or extreme exertion or both, then supplemental oxygen can begin to boost it back up literally in 10-15 seconds. However, you cannot store oxygen, so when the can runs out, you are rapidly back to where you were.
If you see NFL players using O2 masks on the sidelines, that is because they, with extreme exertion, have dropped their O2 saturation, perhaps as much as 20 points. It will come back up with rest and hyperventilation. Supplemental O2 may aid the resting /recovery from simple overexertion (but only if actually desaturated.) I wonder why you do not see NBA players use it? If that few minutes of speedier recovery was real, why wouldn't they use it to help them get back in the game?
Supplemental continuous O2 in the high altitude medical station will rapidly (in a minute) restore O2 saturation towards normal and turn a blue climber pink. However it must be continued, or the climber must descend to higher pressure either on foot, or with assistance, or with supplemental pressure (Gamow bag). However, this response is acutely for the hypoxia and the pulmonary hypertension of high altitude. If HACE or HAPE have started, then recovery is far more complicated than just simple O2 saturation and takes more than a few minutes of canned O2 - more like days (or never).
If anyone legitimately needs supplemental O2 at a moderate Whitney altitude,then they are altitude sick and HACE or HAPE are suspected. As already stated , a few minutes of canned O2 is not enough.
