What are you smoking dude? Saban was a DB coach. he coached linebackers his first couple years then DB's and DC for the next 10 before becoming a head coach No head coach coaches all the players lol, first, it is physically impossible second he is not qualified. There might have been times when he got involved with DBs and linebackers maybe even some on the line but trust me Saban has never coached up a QB or anyone on the offense. Early on in his career he likely had more day-to-day but head coaches are mostly observing and coaching through their assistants.
Do you have any idea how many people are on a football team? There is a reason that, especially on, defense position groups are often split. Often you'll see a safeties coach and a corners coach, inner and olb coaches. The head coach has most of his interactions with the coordinators who then are over the position coaches... its a chain of command dude. What you're describing is like a General going out and running training drills... it does not happen. They have many other duties.
A head coach's job (football) is mostly logistics. Similarly to baseball. Basketball coaches can get more involved because the team is smaller. Trust me most head coaches do not know every member of their teams outside of names and positions maybe. To coach kids you have to get to know them. At the high school level coaches have more hands-on because of 1 smaller team, 2 fewer responsibilities, 3 smaller staff. Even at that level, the head coach is totally dependent on his assistants and rarely know all the kids in the team very well. The stories you hear about kids talking about how hands-on their head coach was.. its because those kids were special cases. Either they were standout athletes or people he took an interest in for some other reason but the head coach literally does not have time to spend directly coaching players. His job is Game planning, personnel moves, fundraising, glad-handing, PR, recruiting. A head coach is 60% manager 40% salesman.