A few years back I posted a rant about non-mission-critical information in woodwind methods textbooks. This is a course primarily for instrumental music majors, who will go on to become school band or orchestra directors, and who need a crash course in the playing and pedagogy of each instrument that will be in their future ...
Good clarinet playing requires a high voicing. That's why your clarinet section is flat and tubby-sounding. 
Tone exercises are useful, sort of. Read last month’s post about tone for a reminder why tone exercises are only part of the process. Here is what tone exercises do: Excellent tone exercises demand solid fundamental tone-production technique, providing a chance to habituate useful muscular actions. Trevor Wye’s “Flexibility I” flute exercise is a perfect example. (I suggest you buy the whole Trevor ...