A lot of people go to school for a very long time, and (or sometimes or) then go on to practice for a very, very, very long time to take really good pictures.
After years and years and years of practice, then those people can start to get to the point where they can just take a picture without "thinking too much about composition." But that's only because they've been practicing composition (and all the other parts of photography) for so long.
Amateur photographers who consistently think about applying even just a few of the basic rules of composition (rule of thirds, etc) often have photographs that turn out much nicer looking than amateur photographers who "let instinct take over."
After years and years and years of practice, then those people can start to get to the point where they can just take a picture without "thinking too much about composition." But that's only because they've been practicing composition (and all the other parts of photography) for so long.
Amateur photographers who consistently think about applying even just a few of the basic rules of composition (rule of thirds, etc) often have photographs that turn out much nicer looking than amateur photographers who "let instinct take over."