Good sight-reading involves comprehension, not just the ability to play right notes. I have trained serious conservatory-bound high school students to sight-read efficiently by ignoring the notes and concentrating on articulation and dynamics. The result is comprehension. In the case of my two young students sight-reading Schumann at the piano today it involved laughter -- right away! They were intrigued, motivated to go over the piece to get the notes right but for the right reason. They had a wonderful time. They got it.
The high school students who went on to take conservatory entrance sight-reading tests reported that the tester was sure they already knew the test material.