I used to run the shot clock for a local college team, and it could be a nerve-racking job at times. I had to keep an eye on the ball while the clock wound down, and reset it as soon as the ball hit the rim or backboard. If the officials blew a whistle, I'd also have to stop the clock. I'd also have to keep track of ball possession, which could change in a flash. It was a lot to juggle at one time, which is why I was happy to give that job up when I graduated.
Personally, I don't see how players learn how to keep track of the 24 second shot clock while they're on the court. There's so much going on with passes and steals and positioning already, so getting off a shot before the shot clock runs out is not always easy.