@BonTheCat
As we both know, the 'endgame' position you show, clearly has a lot of pawn moves and captures before it can even be a case of the 50-move rule.
Not necessarily (but it usually would).
and my point was simply this, for how long do you have to defend before you would be allowed to claim the draw?
Would you say that all games should be terminated at 50 moves if you've managed to defend up till then?
In other words, your example with the starting position is completely irrelevant as it's likely to be a made up game between the two players.
Yes, I'm saying that the 50 move rule should stand. OK, if there's a general agreement to change it to 75 or 100, I'm fine with that, too (although most tournament organizers would probably gnash their teeth).
The point is that I don't think there's any merit in having a different number of moves depending on the position, because where do you draw the line? (I've already shown an entirely plausible position which is won in 549 moves with 503 moves without captures or pawn moves.) Nor do I think there's any merit in rewarding one player extra moves on the basis of him 'making progress' (or not awarding him more moves if the arbiter thinks otherwise). As Nunquam points out, how do you define progress? Also, as yourself has pointed out, we're making mistakes all the time when playing, so why should it matter more, or less, at the end of the game, and why should it matter more or less depending on whether you're winning or losing? There's no logic at all to this. We could easily see a situation where one player was outplaying the other, and then blundered, ending up with K v KBN. Should s/he be treated more leniently as a result of that? After all, s/he was winning for the first 70 moves of the game. In my case, it was the other way around. My opponent played better than me most of the game, and I grabbed the last chance I saw of saving the game, asking him to perform the B+N mate. Should I be punished for the fact that my opponent didn't know how to do it?
I don't know about you, but a great deal of the fascination of chess lies in the fact that you can throw away many hours of hard, painstaking work where you've slowly accumulated one advantage after another. It's a game of brilliancies and blunders, and I can't see anything wrong with tenacious defence being rewarded just as ferocious sacrificial attacks and strategical masterpieces are.
@BonTheCat
Also, you're perfectly entitled to play on in K+R v K+R or K+N v K+N, but few arbiters would reject a claim made long before 50 moves, other than in a game with a blitz finish (and then the game is just being decided on the clock). Where should we set the limit in such cases?
That's actually the main point of the rule I suggested. Normally those positionswould be drawn at the start and end of the draw claim period, so a player would be allowed to claim a no progress draw. After 50 moves in that case.