In learning music one thing to consider is how much you should work on a particular composer's, artist's, or group's songs. If you are trying to maximize your variety and breadth of learning, then work on pieces by many different composer's, artist's, and groups. You'll get lots of varied input, approaches, techniques, and ideas as you work out their songs. If you work on 2 or 3 songs in a row by the same author, though, you are narrowing your variety and creating depth of learning. You're now becoming skilled at this particular musician's approach. It's not wrong to focus; it's a great tool for in-depth learning. But unless you're trying to master a particular artist or group (or you want become a clone), don't do more than 1 song by a certain author before you do 4 of 5 by others.
If you play it more than twice, you're not sight-reading, you're practicing. Working sight-reading = play much music, but only 2xs through.