Ok, but if I judge a position needs ~1 minute of visualization and you're taking 8 minutes a move I'm going to assume certain levels of jerkattude exists in my opponent :p
i.e. if you're playing at a reasonable pace I probably wont care when you resign.
That's probably what I would do if I were to play out a stupid position -- just leaf through it real fast to be as sure as I desire. I simply get that desire to be as sure as possible -- nobody should have to be uncertain about a position when they resign, and playing on helps for that closure.
Do you see supergrand masters playing out a game to mate? They know what is excess in their sphere.
And, of course there are billions of dead lost positions. When I was 8 years old I could win with king and queen vs lone king and then king and rook vs lone king and that was way back. I do not really think a 1400 rated player is weaker than I was, a novice, when I was age 8. If they think they can "learn" from playing out a king and queen vs king endgame then they are not really 1400 strength.