QUOTE(randomsabreur @ May 24 2011, 05:50 PM)

I can usually spot potential banana skins on a quick scan... (flute) But 30 seconds is unbelieveably quick - I run out of time far too quickly.
I did approach the Board about this, maybe as much as 20 years ago.
In those days the performance section of GCSE music included unprepared performance and one option was sight-reading. They were invited to play through the test twice (though with no appreciable "preparation" time) and were then marked on the better of the two. I asked the Board if they didn't think this would perhaps be a good option, since it would probably not take up much more time, if any. Their response was that it wasn't always easy to assess which of the two was the "better" (??just give them both marks and use the higher of the two??) and that often candidates tried it through once with one set of mistakes and a proper play-through with a completely different set of errors. I can't see what that had to do with the decision.
How often, in "real life", do you need to play something at sight?
1.When you're playing with other people (orchestra, chamber music or accompanying), which means you can't stop and correct - if you get hopelessly lost (not your place in the music, but your place on the instrument) you're likely to stop playing for a beat or two until you find your way back in. You don't really do that in a sight-reading test, though, marking time like that. The second time you try it, hwever, you may well fare better. I tell my pupils that what's really important in sight-reading is what happens the second time
(The exception to this is if you play for dance classes, when you [/i]have[i] to go on playing even if you've got into entirely the wrong position, as the rhythm is all-important, but then you wouldn't normally have that job unless you were a fairly proficient sight-reader.
or
2.When you're playing by yourself, usually to start learning the piece. There - though I'm ready for all the posts from people who say they don't do this - the odd mistake probably doesn't matter, but if you've wandered off in the wrong direction, you'd be more likely to re-start again at the beginning of a phrase, wouldn't you?
I have certainly met one person who said she always looked through a piece she was going to sight-read for herself, before ever putting her fingers on the piano, but when I asked why she thought that was better, she said it was good practice for when she had to do it in the exam. Which I thought was rather putting the cart before the horse.
When I'm trying it at home for myself for the first time, I'll always go straight into a piece, taking in the tempo, key-signature, time-signature etc "on the fly", and work out how to play it as I'm going along. Then do it again better.