This may be a useful way of involving yourself with playing your instrument at times when you feel tired or uninspired. When we learn to play an instrument we are expected to practise it in a certain way - to master scales, arpeggios etc, and to achieve technical fluency. Sometimes, however, we may not feel like tackling this demanding task. For example, if you had a full time day job you could arrive home tired, wanting to play your instrument but not having the energy to really concentrate fully on improving your skills on it. Alternatively, you may have reached an impasse musically, feeling as if your playing has become stale. This practise method offers an approach which is technically undemanding, but which leads to a concentrated involvement - it can also help to refresh your attitude to music and thereby to play in a more relaxed and unselfconscious way.
I TAKE your instrument and 'scribble' on it - that is, let anything come out, don't think about the sound you are producing, just keep a rapid activity going. You should be detached from your activity in the sense that your playing is undirected - you are not trying to play a tune or anything specific, you are merely playing. You could be looking out of the window or at a picture whilst keeping the rapid activity going. Don't worry about being "musical" - there is nothing that you can do on a musical instrument which does not in some way involve the rudiments of music.
II GRADUALLY allow yourself to listen to the sounds you are making (as in Stage 2 of Triangle). Do not change the way in which you are playing,
III FIND a phrase within your scribbling which attracts you, and isolate it.
IV TRY to get the phrase totally under control down, repeat it over and over again. Slow it down, repeat it over and over again.
V PUT it into a rhythmic context - decide where it would fall in a count of '1 2 1 2'.
VI REPEAT it rhythmically until you can play the phrase without conscious effort.
VII AGAIN, detach yourself from the activity and listen to it until it suggests a natural extension to you.
VIII ISOLATE this extension from the original phrase and work on it to articulate it precisely as you did before (points III-VI).
IX REATTACH it to the original phrase, and follow the same process of detached observation until it suggests a further extension. Then repeat the process with this new phrase.
CHECK
In your scribbling you have been playing as rapidly as possible. The phrases which come out of this activity will therefore be on the edge of your ability you will be stretching yourself in trying to bring them under control. This practise method therefore allows your skills to evolve in a personal and creative way. It could be viewed as a method of natural composition, since you are inventing the phrases yourself, and developing them in a linear fashion. This can also be an aid to improvisation (which by its nature is less repetitive than this practise method) because it focuses detailed attention on the musical ingredients which exist within improvisation.