Does it matter what note students start their scales/arpeggios in the exam (give or take an octave)

No.

I would say if it's C, D, E or F, then start above middle C (RH)and LH an octave below. If G, A or B, then start below middle C. it's just more "comfortable" to reach. (on the piano)

Not really, although one hopes it will be on the starting note of the scale requested

And obviously make sure there is enough octaves left to play the scale. You wouldn't want to start a 3 octave scale 2 octaves from the top of the piano now, do you !

No, indeed - I did that in my grade 6 piano, and although the examiner asked if I wanted to do it again, I think I still lost marks for it!

You do mean on the piano? It states clearly in the regulations it doens't matter which octave you start on... however other instruments are more prescriptive.

Perhaps because certain octaves are more difficult than others on wind......

Oh, didn't know that.

Learn something every day!

Yeah this is on the piano. I thought that if a child was playing D major for example, and the left hand was placed on the D just above middle C and the right hand an octave higher, that this would be a little, what's the word....weird....am i being picky?

No, you're right. That's weird.

You have to think about where you are sitting in front of the keys on the piano. Why make life difficult for yourself by playing a 1 or 2 octave scale , starting above middle C with BOTH hands and stretching unnecessarily. It also ain't good for producing a nice even tone.