It is quite common for students or their parents to ask their teacher to work on some band pice they/their child needs to learn or something that interests them. Of course, this is perfectly fine – but only up to a point.
If you want to get the most long-term benefit from your music lessons, it is almost always best to let your teacher take you through the bespoke program they have designed for you. Trust their professional judgement based on their experience, training, and expertise and let them take you or your child through the educationally-planned sequence and scope of work they give you.
A series of ad-hoc lessons (“this week, I’d like to work on x, y, z”) might solve a short-term problem or passing interest but isn’t viable long term. It is not effective to use private music lessons just as extra practice for band pieces, for example. You’ll get the most lasting benefit from learning how to play better: not just this piece and that piece, but everything, overall. That is what a professional instrumental teacher can offer (if they don’t or can’t, then maybe consider a different teacher).
Students sometimes want to play things that are beyond their current level of technique. Sure, do it for fun occasionally, but it is better for you as a student to really be able to play rather than to fumble through things and have to engage in a shard fantasy with your loved ones that is actually sounds good. If you’ve ever seen the early audition rounds of TV singing shows, then you’ve seen this in action. Someone butchers a song that is far beyond their current level and is outraged when the judges call them out on it. Don’t be one of those people. Instead, take the time to learn to play properly with effective technique.
Trust your teacher to help you achieve that. They are the expert, and you’ll do best if you accept that expertise and let them teach with minimal interference. That’s a great way to benjoy more effective lessons and reap long-term, lasting benefits.