back in the day, as an undergrad, my private teacher told me if I wanted to improve my "sight" reading skills, just to read everything I saw. Songs from a Hymnal, piano books, everything that I could get my hands on. As an educator, I have maintained that same attitude. I try to read something new every day, even if it's from a technique book or a short piece. The beauty of the prepared sight reading collections is the consistency between instruments and parts.