I do the majority of my practicing in my office at university. There's a busy hallway right outside my door and a window which looks out into the atrium of our main music facility. There are almost always people near enough to my office to hear me practice in real time. I was thinking about this recently and began to wonder who might be listening to my practice sessions from the hallway.
I'm not suggesting that people camp outside my office door and eagerly await the arrival of my first notes every day (as cool as that would be). However, the thought that people walk past my door and hear what I'm working on reminded me of something I've heard a lot of musicians say: always sound your best.
The sentiment of always sounding your best is well-intentioned, but impractical and unsustainable. It's also in direct contradiction to one of my axioms, which is that practice is for problems. If you constantly attempt to play your best, you'll be stuck forever playing like you do right now because the fastest way to improve is by attacking your weaknesses. Attacking weaknesses means making mistakes. Making mistakes means sounding less than your best. The goal is to improve every time you sit down to practice.
People walking by probably think that I don’t perform as well as I do since I spend most of my time working on weaknesses. They walk by and hear me sounding my worst, precisely because I'm fixing the highest priority problems. I think certain people are surprised when I perform because there’s a big difference between performance preparation (practice) and performance. Performances are a very different product than practice would indicate. This is because I spend so much more time hashing out problems (improving weaknesses) than working on my strengths.
Here's another way to look at it: maintain strengths, but focus on weaknesses. Better yet, make weaknesses improve so much that they become strengths.
It's best to sound your best in certain situations. Find a way to peak for each performance. If that's not possible, decide which performances are most important to you and peak for those. Ultimately, you’ve got to decide what’s more important to you: improving or sounding your best.