I see many people say "quality over quantity" but why is 15min better than 1 hour? It's as if quality drops after 15min... Can someone explain this please?
As long as you understand why a move is the best move and analyse it properly, you are ready to move on to the next puzzle. If you do that 10 times a day or 100 times a day, the quality will not drop... Or am I missing something?
or should I do maybe less and do some chess mentor courses or video lessons? I want to improve my game asap