The level of a band can change dramatically over the course of a year.
  At the beginning of the school year, new members join and all schools are busy with basic practice. Don't start practicing difficult pieces at this time, but rather wait and build up the basics until the new student are able to join the ensemble.
  Reading music is also an important foundation.
  First, practice playing one note with proper tonguing. If members of your band can't do this, no piece will ever finish properly. It's a waste of time to move on to further practice until the whole band can play one note.
  Once you can start the first note properly, you can connect it to the next note.
  There may be times when you have to play during the first semester, but even in those cases, be considerate and have the new students play only easy parts according to their level. Similar consideration is needed for new members who join in the middle of the school year.
  Always make sure that each member can play their part reliably.
  They will improve rapidly by the end of the first semester, and will be able to play a variety of pieces from the second semester.
  Concerts and festivals are held in various places from the end of the second semester, and the level of each band is the highest by that time.
  Even at this time, I think it is better to put more emphasis on practicing each member rather than the band as a whole.
  The more each person improves their ability to play their own instrument, the easier it will be to play in an ensemble.
  What we must not forget is that The school band "starts from scratch every year."
  When teachers hear the sound of a band that has become best at the end of the school year, they tend to think of the next year as an extension of that, forgetting about basic sound making, and starting with pieces that are more difficult than the previous year.
  This is especially likely to happen if there are many members remaining from last year, but please pay attention to the level of students who have just started this year. If you can be patient for 2-3 months, the new members will be able to play like the members from last year.