Recently I tried this puzzle:
http://en.lichess.org/training/20318
and saw the motif Nf6+ leading to mate. No credit. Because it takes a whopping one move more to checkmate. Interesting that lichess puzzles are so strict. In some ways, I appreciate having to see everything and trying for the absolute best and quickest way to win. I may lose points, but I learn something. On the other hand, it can be frustrating to not get credit for something that wins just as well, one more move not likely mattering in a practical game.
http://en.lichess.org/training/20318
and saw the motif Nf6+ leading to mate. No credit. Because it takes a whopping one move more to checkmate. Interesting that lichess puzzles are so strict. In some ways, I appreciate having to see everything and trying for the absolute best and quickest way to win. I may lose points, but I learn something. On the other hand, it can be frustrating to not get credit for something that wins just as well, one more move not likely mattering in a practical game.