One thing I've noticed is how players (especially less experienced and those in the BB world) refer to notes as 'Top C' or 'Top A'. This is not really the case as there is another C above this which may players can reach and certainly A's etc. I believe it is this perception of 'Top C' which goes a long way to preventing players reaching other notes above this. I myself can play double top this and double pedal that but do not give the notes these names and therefore reduce the pressure on myself to play them. You find that more experienced and professional players simply refer to the note by its name and miss the 'Top' out completely. With my students I do not teach 'High' notes or 'Top' notes instead they are upper of lower and are no more difficult than each other. Another thing I do is to start them playing C (Bb Concert) In the stave, not below it and extend the range from there. It is then only an octave to ('Top') C and and octave to ('Bottom') C. I find it gives students ability to play all the range more easily. For example I have a Grade V student who can play D/Eb and octave above middle C (Top D/Eb). I therefore put it to all of you that we should stop calling notes 'Top' this or that and simply refer to them by thier name.