I've mentioned this in other threads, but will repeat it here.
I usually resign when I know that I could flip the board 'round and beat Magnus Carlsen. Exceptions are when my opponent has asked me to resign.
Sometime I resign sooner.
If a player does not resign against me, I may choose to practice knight and bishop against lone king.
Robert, you're not making any sense. We're not talking about "winning" positions, we're talking about "WON" positions. K + Q v. K isn't a winning position. It's a won position. The other side has no chance of victory, and continuing to play on is spitting in the face of the winner. If I insult them for it and they learn, great. If they never forget it, that's ok. If they never play in another tournament again, no big loss. Learn to play the game, and play the game the way it's meant to be played. Boxing referees stop a fight before one side dies. In chess you need to be your own referee.
Perhaps you have missed the three occasions during this discussion in which I already acknowledged that there is nothing to gain by playing on with a lone king against a king + queen (unless you are a total beginniner - in which case - yes, you still have something to learn, even in this situation).
However, the K vs K + Q scenerio is NOT the only situation that is under discussion here; it's just the situation YOU have decided to focus on. There are many other occasions in which a player may potentially resign, or be "expected" to resign. I have had an opponent calling for me to resign after I blundered and lost my queen, for example. I find that ridiculous, since as far as I'm concerned, it's still possible to play on and win. Perhaps that's not the case with top level players, but again, I'm not a top level player. Neither was my opponent. Neither are most of the people playing chess on this site.
The point being, lower to mid level players should NEVER be too hasty when it comes to resigning games, since they still have much to learn and everything to play for. And yes, it is still possible for beginners to learn something from apparently hopeless situations, since it helps them to understand how to conclude the end game. Perhaps you don't need to play out K vs K + Q repeatedly, no, but that's just one potential end game scenario.
Your analogy with boxing matches doesn't appear to work very well. Perhaps you misunderstand why referees stop boxing matches. They don't stop matches because one of the boxers is "winning". They stop the match because one of the boxers is unable to defend himself, and if he takes any more punishment, he may suffer permanent injury or death. I don't know what sort of chess matches you like to compete in, but I've personally never felt that my life was in danger while playing chess, even on occasions when I was losing badly.
And I'm sorry, but I find the notion that you take personal offence and insults out of the fact that your opponent wants to play on to the end of the game overly sensitive and more than a bit precious. Perhaps on some occasions it's misguided and clueless for your opponent to play on in a lost game, yes. But there's no reason why you should take personal insult from that. It is only a trivial game involving moving bits of plastic around a board afterall.