It gets hard at 500 rapid, or 400 blitz & bullet.
I don't know, middle game might be the hardest for me. But I don't care. I love to experiment with moves even if I don't know if they're good or bad. I could NEVER play the same over and over in every game. I can only play by intuition.
I thought of this question, more and more recently. When I was a young player the opening was difficult, then middlegame. Most of us can play the open and not think too much, but that happens also. The question is, when does the game get difficult, for you?
Don’t come at me with “depends on the position” because that is basically the same question. lol