What some overlook is that at the senior level, defense in the vicinity of the ball needs a "bunch ball" approach. The deadly flaw isn't bunching around the ball, but failing to have "balance" away from the ball. My own view of coaching and bunch ball is that if you don't teach players anything but how to play on the ball, then naturally they will all chase the ball. The first objective ought to be to teach how to play on the ball. How to support off the ball comes later. My own view of teaching tactics is that you direct the player's actions by how you design the activities rather than telling players what to do next. Let them learn what tactics work best by trial and error and watching what works best for other players. You aren't teaching anyone how to play if they aren't making the decisions and solving tactical problems. Otherwise you are just teaching them how to follow orders.
Problem: little kids are bunching up What happens in most practices: "They're young, we have to teach them a lot of ball mastery, 1v1." Which is probably the correct thing to be teaching, but then don't put them in 4v4 on the weekend and expect their 1v1 training not to show up. I think the Belgians have it right, 1v1+2GKs at the youngest ages. Coach lets them try a rondo: ball keeps escaping the triangle "This is too advanced for them, they clearly can't do it!". They couldn't do ball mastery very well either but we keep making them do it, wait for it, until they get better. We don't teach them how to pass and receive and basic shape and spacing found in, say, a rondo and we expect to them to do it in a game. Much of the National Youth License is about playing fun, sometimes non-soccer, games that teach cooperating to achieve an objective. The objective is usually getting a ball from point A to point B in a fun way. The underlying recurring lesson: how can we get the ball "over there" together. With my U12s, they are too spaced out on the 80x55. They can't support properly, they have too much ground to cover in defensive transition, they are outnumbered near the ball. When it was 60x40, spacing wasn't a problem they could be touchline to touchline and not be too space-y. I'd love to see an extra year in 7v7 where the space is just a tad small for them. Modify no punts over midfield. Let them play in a tight space. Let them play in a space where breakaways are almost impossible. And in that last year, you get rid of the buildout line.
I think bunch ball is a good time to focus on dribbling and shooting; those are the most fundamental parts of the game. In the most simple form, 1v1, it is defend-dribble-shoot, defend-dribble-shoot. So you know, when life hands you lemons. As kids age they become less ego-centric and can mentally understand the concept of working as a team, and that makes it easier to work on passing. Shooting on goal also helps with passing since it's a very similar action. So I say dribble and shoot till the cows come home. For shooting/passing accuracy I recommend a simple game that can be done at home. Simply try to knock over a plastic cup from various distances. Can use a plushy ball if worried about damaging your little knick knacks. My kid really enjoyed that game. We did it from all kinds of angles, kinda like that youtube guy dudeperfect, he does trick shots with basketballs, so we did various "trick shots" with the soccer ball, for example putting the cup at the bottom of the stairs and kicking the ball down from the top of stairs.