Ideas on practicing
Nadina Mackie Jackson
As a result of preparing two particularly challenging pieces this fall (Silver Angel by Constantine Caravassilis & Sonata Concertante by Nikos Skalkottas), I am in the process of compiling & publishing my first comprehensive book on technique.  And thinking a lot of what it means to practise. 
If you have a musical goal and a powerful feeling of how you want it to resound, you will find the path, or rather, the many branching paths.  Astonishingly, they will occasionally link at a point that is not visible from your present perspective.

The Big Picture is created from an ever-flowing fountain of details.  And sometimes it is a bursting firecracker fanning into the night sky that has to be lit over and over.
How many hours to practice is not the question.
Rather, I suggest a certain number of hours so that you can learn how many hours it takes to develop a continuing awareness of your practice, e.g. building on your work from day to day.  If you practice the same thing every day, it will not longer be the same thing.  It will be better, even if you are not (yet) the perfect embodiment of practice perfection. 
Practice is more than blowing into your bassoon though that is important, too.
It is much more than doing what your teacher says. Though that is important, too.
It is about the discovering the depth of detail required by your mind and body to perform music in the way that you crave.
Practice is done by the brain.  The brain is inextricably linked to the body; there is no hierarchy of superiority, only of function. The brain has the capacity to grow and develop based on challenge (at least according to the book I am reading at the moment, The Brain That Changes Itself by Norman Doidge (Viking Press)), analogous to the way that muscles grow and develop.  Challenge your brain every day, and train your body, and thus it is safe to say that you begin to think of practice as something that transcends a finite number of hours in the day.
Through developing routines and patterns, you develop the route to greater freedoms.  Like a map of a country that is constantly developing, detail is added to the basic structure as your perception becomes increasingly refined.  Repeated gesture eventually becomes part of your instinct and you move to the next challenge.
If you aim to practice four hours (or two or six) in a day, you can find those hours at different times and different places.  Then the luxury of having an equipped studio will be exactly that, a luxury. 
If you practice every day, then the odd phenomenon of relatedness kicks in of its own accord, and when you hear an illuminating thought from an non-bassoon source, it will alchemically shift in your spirit to become “something to try” the next time that your bassoon is in your hands.
If you practice every day, none of the other, non-practicing moments are wasted.  With the constant reference of your practice, you can relate other information to this skill.  Distressing rehearsals can be reframed as a means of concentrating on a specific aspect of your technique (e.g. madly practicing double and flutter-tonguing during an out-of-tune fortissimo brass chord in wind ensemble, don’t tell them and I won’t either); time spent on the bus can be an opportunity to imagine a cadenza in shape and spirit.  Imagination is a huge part of practicing.
Stability lies within yourself.  You are the reference for the reeds, the instrument, the sound, and the goals.  Find the centre in yourself to maintain pitch integrity.  The more you require of yourself, the stronger this feeling will become.
And I do think discovery lies in conscious exploration (some people call that research).  The simplest route is via polarities:  e.g. fast scales and slow scales; jubilant scales and dismal scales… you pick the adjectives.
Practice structure. Be systematic and thorough; the wild imagination must be grounded in a secure foundation.  In this way, you develop mental security and a strong embouchure (mind & body unite).
Practice emboldenment alongside refinement.  Through polarities you will find your style.  Your style will emerge anyway, but the conscious understanding of its existence will allow it to blossom as a real voice rather than a set of limitations.
Practice confidence which, simply put, means consciously attempting musical challenges that frighten you.  Add to that trust, faith and courage. Eventually you will develop grace in moving through obstacles.  There will always be obstacles.  And you will not be stopped by them.
I have to practice now.