There is no reason for it to take years and years. I would recommend writing to a scheduler at a company whose shops you want and ask what you can do to improve your application. Like I already said, sometimes all you have to do to stand out is to ask.
This is assuming that you already do regular, good quality work for that company. If you have a shop for them this month, put in a little extra work. I have found that including details that are not asked for can get a rave review. It shouldn't be a novel, but writing a coherent narrative vs a series of sentences. Maybe you already do that, but for years, all I did was the bare bones writing. I got consistent 10 ratings but the comments changed after I adjusted my style.