I've seen a few folks here get dragged for "not following [their] training" in the wake of accidents or near misses, particularly in cases where a buddy or even a DM/guide ignored their "low air" signal or offered their octopus instead of ascending. I've reviewed my PADI OW manual (version 3.02) and it doesn't address this specific scenario. It does say not to risk running out of air underwater, but it certainly doesn't say not to share air in order to avoid that outcome; in fact, it teaches that sharing air is the preferred way to deal with an OOA situation, if possible. It also teaches that the first step in ascending is to signal your buddy. It emphasizes that avoiding buddy separation is YOUR responsibility. It teaches that, if you and your buddy become separated, the normal procedure, unless agreed otherwise with your buddy, is to search for each other underwater for a full minute before surfacing to try to find them there. (It also doesn't go into what to do then if your buddy doesn't surface.)
So I'm curious. Are there other training agencies that do explicitly teach that you should ascend alone once you reach a certain tank pressure even if your buddy refuses to come along? Do they get into exceptions (like areas with heavy boat traffic where that might not be safe?) Or do people think that should be inferred from the lessons PADI imparts as summarized above?
Are there other "Plan B" (or "Plan C") scenarios that get more attention in some OW courses than others? For example, running just slightly low on air, such that you can either surface with 500 psi or do a safety stop but not both, getting lost underwater, dealing with nausea/vertigo and vomiting underwater, etc. Not looking for answers as to what to do in those situations (though I anticipate that people will end up discussing those things); my question is what, if anything, do the major training agencies teach about these things in their OW courses?