I have seen multiple instructors telling students to dive an air setting. Again, IMO, that alone is not especially dangerous but it gains nothing over setting your computer correctly, setting a comfortable (to you) gradient setting and then using the gray matter between the ears to say, hey, let's go up or shallow up or end the dive before approaching the NDL.
I have several times been on boats or at a dive locations where divers set for air and exceeded NDL and locked themselves out or pushed MOD depth.
I certainly can and do run hour plus dives on 80cf in that magic 60-100 feet zone. Tank volume is not for me (or many divers) the limiting factor, it is NDL.
I understand DCS is scary and inconvenient if it happens but I think that card is over played. Anecdotal, yes, but I have done thousands of dives and due to application of some common sense have never been bent. I have seen people get bent and they all did something really stupid and one fellow paid for it by spending his life in a wheel chair. Now that is inconvenient

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