Listen, I was a student, too, and I have gone to my share of lessons unprepared (but I only did this once for Jan at North Texas, and received a well-deserved lashing for it). I have also tried to hide this fact, or cram before the lesson, in order to not disappoint my teacher.
It never works. As a teacher now, I can tell you this: we can always tell. It would be much better for you to say, hey, I haven’t looked at this, I’m sorry, than to fake your way through something. Chances are I’ll be disappointed, but we can find a way to make the lesson productive: Either you can demonstrate how you WOULD have practiced it had you made the time, or we can work on some other aspect of technique or theory.
Now, that doesn’t mean we can spend every lesson avoiding what you didn’t have time to do. I expect that my students find the time during the week (it doesn’t have to be much; 20-30 minutes a day maybe, is better than bigger chunks with gaps in between) to work on what I’ve assigned. You take lessons because you want to progress beyond the skills you need for band, or to match them, or to get access to different music than you might otherwise. There are lots of reasons to take lessons, and lots of reasons for me to have certain expectations about how you will act upon them.
So, how do we get around this dilemma? How do you practice ‘enough’ to ‘fool’ me? Well, first of all, you don’t need to fool me. I am here to help you, and so that means if something gives you trouble, I should be the first to know. If you’ve worked for ages on these two bars and just can’t get them, maybe I can help you move beyond them. You don’t have to be perfect, just prepared.
Now, time management. Kids, and adults, these days, are BUSY. Does anyone know what free time is anymore? How does music fit when it competes with homework, athletics, clubs, friends, downtime?
You could always think of your music practice as homework. 30 minutes of something you have to do every evening even if you don’t have a class the next day. You could think of it as athletic conditioning, which is constant. You could envision it as a project you do for a club that ensures your participation is 100%. You could make music with friends or practice as a way to relieve stress from everything else.
There’s no right or wrong answer here. The only right way to go about managing your practice time is to make sure you’re focused and consistent. And if you’ve been focused and consistent in your personal practice, that will show in your lesson. That will give us something to move forward on.