What kind of music do you want to be able to read? Presumably the music you like and want to play. So read that. You will always be reading new stuff you don't know, not the same thing over and over, so I'm not sure how never making any progress is a possibility. Sight reading/playing difficult music is not easy, sounds like you want a quick way of learning the skill, which doesn't exist.

    A fellow went to a Zen master and said, “If I work very hard, how soon can I be enlightened?”
    The Zen master looked him up and down and said, “Ten years.”
    The fellow said, “No, listen, I mean if I really work at it, how long—”
    The Zen master cut him off. “I’m sorry. I misjudged. Twenty years.”
    ”Wait!” Said the young man, “You don’t understand! I’m—”
    “Thirty years,” said the Zen master.