Starting each rehearsal with unison/octave warm-ups has always been essential with my bands. It is difficult for players to match pitch well unless unless they can all produce "characteristic tone qualities". Matching pitch & TONE should be a daily goal. Having 1st chairs or directors demonstrate musical passages then adding players, encouraging everyone to listen carefully matching pitch and tone. I have always been a "tone before tech" teacher and it's worked well for my groups(a few HB's). I don't care how many notes a group can play. If they cannot produce characteristic sounds no one will want to hear them.