ALL WRONG!!! (Except for palpi, ironically... Very short response but entirely true and effective)
Believe it or not, scales and arpeggios improve sight reading drastically; you just hafta read the music while you are doing them or just make sure you are focused on the scales movement.
Also try different patterns with the arpeggios, (Ex: Instead of C E G up the octaves, try C G E up, E C G down or something random)
This will allow you to recognize musical patterns that you have played in the piece you are attempting to sight read.
Also, get a drum/percussion instructional book. That will help your brain lock in complex rhythms in and outside of 4/4 (Like exteremes of 9/4, 9/8, 12/8, and, in a really rare case 14/16) Then apply them to your excercises.
Also, when you practice, take it slowly. If the tempo reads 120 bpm, take it at like 50-75. I am piss poor at sight reading Clarinet, and this helps me get through God forsaken pieces like Procession of the Nobles and Rocky Point Holiday. I can even hammer out the first chunk of Beethoven's Pathetique Mvt. 1 and I am an intermediate pianist at best.
There are also solo song booklets that come with CDs that have an ensemble recording. I used to sight read one piece every week when I was learning Trombone. That helped greatly.
Trust me, I am literate in Guitar, Percussion, Baritone/Euphonium/Trombone, Clarinet, and the Piano; am a music major in Music Theory and Composition, and a firm believer of the word practice. Do it ALOT.
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Why Crimson King is wrong:
Music Theory does not change talent or really aid a music player. It only helps them understand what they are playing. When improvising guitar, knowing the circle progression (I-iii-vi-IV/ii-V/vii*) is fun and all, but does not help sight reading. It helps predict the phrase and nothing more. Also, pianists have much more options chord-wise than guitarists. We strum our C Chord without reguard to whether to leave the bottom string off or not. The pianist has to worry about which keys make more sense with the passage and adjust.
Why CRASHiC is off:
Those music camps are expensive as hell and not everyone gets accepted. Pianists have even more difficult of a time getting in because pianists are all too common. If the request came from an oboeist or a bassoonist with plenty of money in the family, it wouldn't be an issue. Also, sometimes students are neglected as there are really talented musicians that hog all the glory.
However, if one got in to a workshop, it would improve their musicallity.
It's a good option, but not one for everyone...
Good call on the time signatures though; that was right on the money.