Tuba/Euphonium friends, here is another little video I did on the characteristics of the slots in the lower register in particular, and how free buzzing is related but different, and if you try what I am demonstrating, I have found that students greatly have improved their focus and agility and tone quality doing this! If it is helpful, please feel free to share. If it already intuitively obvious, then you are already probably playing very efficiently. Every day I try to improve my efficiency with these sort of exercises and it does work well.
Thanks! Best regards, Steve