Possession is only useful if it helps the team solve the game.
Six passes that move the opposition, create a free player or improve the next attack can be excellent. Six passes that simply keep the ball away from risk may not be teaching much.
I would coach intention rather than pass count.
Ask players: can we play forward? Can we carry if nobody engages us? Can the next pass break pressure? Can we move the opponent before going through them?
I also think coaches have to be careful not to praise the style more than the decision.
A direct pass into a striker can be the best football on the pitch if it is on.
At U10, I want players comfortable keeping the ball and brave enough to threaten.
Possession should give them more options, not become the option they are always expected to choose.