Great observations trickg! As Clark stated it's "when we practice, how we practice and what we practice." Efficency efficiency, efficiency!!! We need to play to develop the embrochure but it is most important to play smartly. When we are efficient everything is easier and we can develop faster, although it does take a long time to become efficient and a virtuoso player. I'm certainly still in the process as a comeback player but have discovered these very important efficiency ideas from the famous players like, Clark, Gordon, Vizzutti and others. Efficiency is based on air flow. It is very important to have an appropriate set up with mouthpiece and horn to have good airflow for some, I was one of those and found a combination that woks and the air is now moving and endurance has skyrocketed. For me it is not hours and hours of time but the quality of time spent on my practice.