I used to get upset over people I'd lay hands on who wouldn't get well. I was praying one day and seeking God about it when He spoke to my spirit and said, "Healing always comes."
I remember I said, "What do You mean, Healing always comes? Not everybody gets healed."
"I didn't say they all received it," He answered. Then He spoke very sternly to me. "I do My part. And I said they would recover!"
Those words hit me like a ton of bricks. He said they would recover. He never lies. So if He said they would recover, then that means healing always comes. It's not God who's holding back. It's the receivers who aren't receiving.