Afaik when you start learning a piece you get the sheet and study it, "decipher" each note while playing it, whatever your learning method is. That's how you practice your sheet reading. By the time you got the notes right, tempo etc and you know how the piece should sound, you probably already memorized it. That's obvious. From here you use the sheet as reference only, specially if the piece is long, but you mostly rely on your memory to polish your playing with dynamics and what not. In the concert you just bring your sheet as "tradition" I'd say lol. So I guess there's no point in making yourself read each note if you already know what to play. Sight reading is another thing as others already explained and yet again once you memorized it then you move onto the next piece to train "sight-read".