Eventually, you and Frodo will design a randomized trial to determine the most effective method to practice sight reading.
At first I used ultra simple things like the first volume of Sartorio Opus 45 sight reading exercises (find it on IMSLP) going slowly enough that I could play it at a steady tempo without looking at the keys. The later exercises get more complicated so I'd cut myself some slack and allow myself to look at the keys for big jumps once in a while.
I know this does not answer your intensity versus duration question, but it's the best answer I've got.
An idea that some may disagree with – If you are sight reading something over your head, I think it is actually good to repeat reading through it for up to 3 reads in a row in addition to playing at a slow to very slow tempo.
You could train your reading skills repeating the same group of pieces hundreds of times. Noticing the synergy between memory and reading is very important and is necessary with multiple repeats of the same content.
Method of reading to start with:1 read RH alone1 read LH alone2 reads both hands together - as slow as needed
I don't like the idea of reading one hand then putting it together in terms of sight reading skills (or something you should heavily rely on for practice method, there are better ways to maintain both hands eg simplification and bulilding towards all the notes) unless you are a very early beginner with reading skills, but even then you can do easy enough works that you can manage reading both hands.If you are not reading both hands at once because it is too challenging to do so you need to simplify the music so you are experiencing it.
There is nothing wrong with doing some single hand reading especially for pieces written for one hand as that often goes through different clefs. Two hand reading is just something as keyboardist that we really need to get good at unlike other instruments which where often it is only one stave at a time. So reading one hand is fine but one shouldn't really make that a focused effort unless they really are early beginners. If you are doing pieces that are too difficult you csn always read one hand complete while playing only a limited amount of the other, at least two hands ar being played and you also are practicing simplification skills (good tool to use when trying to solve both hand playing).
I guess I was thinking of following: Rather than being able to play a piece without having seen the work before, it is sometimes more important to be able to play a piece having only looked at it for a very short period of time. For example, a violinist says to a pianist - Can we get together tomorrow to read thru some music? Pianist says - sure. Let me know the pieces so I can take a look at them before we get together tomorrow. Violinist says: But I have music with me. Pianist says: Can I stop by now to pick up the music? Violinist says - OK.
I'm specifically focused on forgoing two hand for one hand reading. I'm not sure what your described situation is dealing with
Forget about hands separate then if you believe it is not helpful.
When learning a piece quickly - say piano part of a Beethoven violin sonata to be learned overnight - I would suggest fingering the piece as the first step after a quick first read.
How about let ranjit finger say the 3rd mvt of a Kulau sonatina before reading thru it? Is this ok?
Of course it s not good if your goal is to be able to sight read without any prep - but I am talking about learning a piece quickly - say overnight. How do you learn a piece quickly? Just read thru it? Ever practice any passages hands separately?
If learn piano part to Beethoven violin sonata overnight - you will be reading from the score. I don't think it's possible to memorize in 1 night! Is it okay to practice small sections to learn a piece quickly?
I guess I am talking about sight reading from a score that you have studied for say 4 hours having never seen the work before. Say the piece is 5 minutes long. You will be reading from the score since it will not be memorized. How is it best to learn the piece in this short period of time? I understand this is not true sight reading.
In the case of true sight reading, you play the piece having looked at (but not played) the score for about 1 minute in advance.Reason I raise the question: Sight reading with very short prep is often more useful than true sight reading in real life situations.
IMO: There is no "magic very narrow path" to learning sight reading. It is instead a fairly wide road to travel but staying out of ditches is very important.
Which should one have more of to improve sight reading quickly? Shorter, more intense sessions of say 15 minutes each, or long sessions where you're reading at a lower level but for an hour or more?
I think you are not asking the right question. Sight reading is very common among vocalists.
Some could sight sing, some could not even after years of learning.
Sight reading won't happen overnight. It involves too many things especially for the piano.
There's ear training. You will learn to recognize intervals and triads so that at the end you can read and hear it in your head.
Ultimately, it still takes innate ability and working over a long time.
Different creatures have different functions in the ecosystem. What God left out, you can't put it in.
Sight reading is very common among vocalists. I personally am not a vocalist, but my first music education was not through the learning of a musical instrument. In grade 2 elementary school, kids in my school were introduced to the solfege system and sang before singing from the music staff where the scale can be moved from line to line for different voices. .....
You will learn to recognize intervals and triads so that at the end you can read and hear it in your head.
Actually Ranjit started with different music than I did, and we have opposite strengths and weaknesses. He recognizes chords more than I do, relates them to piano keys more than I do - while I can hear melodies while looking at a score, and those things that come from being a singer and playing a passle of sonatinas when young since it's the only music I had. Said sonatinas were mostly diatonic. And yeah, I probably have some "talent". I'd not bank on that, though.
Ranjit, you and I have different and opposing strengths and weaknesses because we were exposed to and thus focused on opposing things. Whenever there is an imbalance of weak and strong areas, the trick is to focus on the part one doesn't have (much).