I think that most teachers aren’t insane and depressed because there simply is no time. Every day brings a new set of challenges – every day is “small very present doses”. Sure many may be the same as last weeks or last years, but a few of them aren’t, and even if they are, they are so very human, and as such are constant and changing enough to require cleverness, and required cleverness is a charm against depression. Postal work is constant and requires no cleverness – today’s “small very present doses” are EXACTLY the same as yesterdays. Teaching is different in the ways that matter most. By the time you have actually figured it ALL out – by the time you could just run standard protocols for every single event – you will be wizened and wise and beyond insanity and depression, and well into eccentricity.