We all have "good days" or "bad days" in almost all facets of our lives. This is even more true for athletes, and, of course, for shakuhachi players. We feel like we run out of breath sooner than usual, or that our pitch control is sub-par, or our hands don't move their way they should, or...I could go on.
Often, when we listen to recordings of ourselves made on these "bad days", our playing is indeed worse than usual. However, often it won't be nearly as bad as we had perceived it to be. Or, it may even turn out that we only thought we were having a bad day, when in fact we were having a great one!
The reason for this is that our internal "sensor" that lets us know how were playing can become off-kilter. It can lose sensitivity, and we think we are playing very well even though our playing is only average that day. Or, it may be come overly sensitive, so we become super-critical (thinking we're playing horribly) even we’re playing is just fine.
Our "sensor" (which is just another way of saying how we perceive our own playing) always depends on how we feel at any given time. That's unavoidable. Sometimes, though, our moods may throw it so far off that we don't evaluate ourselves realistically.This has the unfortunate effect of distracting us from our playing.
The fact is, almost everybody thinks they have greater variation in their playing than they actually do. The difference between what you may consider a great or a horrible day won't be nearly as discernible to an objective listener. Our actual level of skill is on display when we play, which is a boon and a burden both. And, when playing honkyoku, your soul is on display as well.
So, we want to reduce the fluctuations that the inner "sensor" goes through. The only way to do this is to increase your level of focus and concentration. Ten minutes of Ro every day is just as useful in building up the mental aspects of your playing as it is the physical aspects.