I learned the old-fashioned way, via phonics, and by the seventh grade I was reading Dostoevsky...and LOVING it!
I could “sound out” anything.
An ancient but wonderful method of teaching sight-reading music is “Solfeggio” which is the old “Do re mi” method of note-reading. It works in a similar fashion, by “sounding out” the intervals.
I also sing in the Latin Choir and I often transcribe my harmony (alto) into shape notes so I can grasp and practice the parts that are more difficult for me. The shapes (Do-Re-Me) are amazingly effective in learning new music.
The best can sight-read hundreds and hundreds of songs.