As much as you can get in. But it’s better to do it when you’re able to concentrate. If you’re so exhausted that you can’t really bring your best it might be better to study the music without the instrument. In fact, when we travel–which I haven’t been able to do so much since the plague hit us–a lot of times you don’t have the luxury of practicing only when you feel strong. Sometimes it helps even to lay slowly and quietly at the end of a long day and set yourself up for a good day when you are feeling fresher.
If you have an international flight, you’re not practicing during the flight (although most of us can practice mentally without any instrument to hold onto). Still getting to Europe, for example, can take you near to 20 hours door-to-door. You can’t always practice as much as you’d like. Therefore, you have to be super well-prepared so that when you do go on the road and you have jet lag to deal with, fatigue, your preparation is absolutely secure and you can go on stage in front of a bunch of people you’ve never seen before and play well.
Ideally, I think about five, six hours of practice a day is great, but that can be very difficult to attain, especially if you have a family and you have other responsibilities. It’s rare that I have an entire day at my own disposal where I can decide what I want to do with the entire day. That almost just doesn’t happen anymore.
Even some of the most famous people in our profession are quite open and say that they have to spend so much time planning the tours and negotiating this, and negotiating that, and so a real career is not quite what you might have imagined when you were younger. It’s when you’re younger that you have free time.
When you’re starting out usually you don’t have any money, but you do have time, and hopefully, you can really just focus on your own art. You don’t have kids to drive around or other responsibilities that eat into your purely artistic work. I think that in music, just just like in athletics, it’s great to be able to start young. You don’t necessarily have to practice all that much at first, but having started young, just the familiarity with the instrument, having the instrument in your hands next to your body, is important and very difficult to recoup later on.
People who are gifted athletically can start later because they have great mind/body coordination from being athletes. Having that athletic ability, perhaps they can catch up quicker. The guitar is so dependent on the physical attributes: fingernails, the size and flexibility of the hand. If you have a big hand you can do certain stretches that a little hand cannot manage. But many great virtuosos make up in agility and speed for smaller hands. No one has everything or is without some shortcomings. The work of a lifetime is minimizing the shortcomings and maximizing the talent.
Still, classical guitar technique relates to the body of the player almost as much as is the case for Singers where the instrument is literally part of your body.