Train the pivot: receiving on the half turn with his back to half the grid, setting first time to a corner he checked before the ball arrived, and switching the direction on his own call.
Mark a 20x20m square with a cone on each corner and a marker in the middle. Four players on the corners, one in the middle. The corner in possession passes into the middle man, who plays it first time out to the next corner round. That corner returns it into the middle immediately. Once the ball has gone all the way round, the middle man reverses it and sends the next set out the other way. Corners are two touch, the middle man is one touch. Change the middle man every two minutes.
A passing square where the ball runs along the edges asks almost nothing of anyone. Every receiver knows where the ball is coming from, every pass is the same length, and nobody ever has to turn. Putting a player in the middle and forcing every ball through him changes one thing and it changes everything: now there is a player who has to receive with half the grid behind him.
That is the job of a holding midfielder, described exactly. The ball arrives from behind or from the side, the next pass has to go somewhere he cannot see at the moment it arrives, and the only way to solve it is to have looked before. Scanning is not a drill you can run separately and hope transfers. It has to be forced by a shape where not looking makes the next pass impossible.
One touch for the middle man is a deliberate constraint rather than a difficulty setting. Give him two touches and he will receive square, look up, and then pass, which works perfectly in a square with no defenders and fails the moment anyone presses. One touch means the information has to be gathered before the ball arrives, and the body has to be open before it arrives too.
The reverse is what stops the corners switching off. When the direction is fixed, the corner two passes away can start moving before he has any right to. When the middle man can send it back the way it came, every corner has to be ready on every ball, which is a small thing that keeps the tempo honest for the whole group.
Rotate the middle every couple of minutes. It is by some distance the hardest station and the only one that gets tired, and a group where only one player ever plays there has trained one player.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.