During practice you should stunt on lines. This makes it clear when stunts are moving side to side, which is more noticeable to judges than moving front to back. Not only does it make it clear to you, the coach, it makes it clear to the stunt group without the need for you to say anything, and having self-correcting athletes is the ultimate goal.
Remember, I’m saying you should do this at practice. In competition do what makes your routine look the best.
This is something I made my teams do in the past, but got away from. Kenny Feeley of Spring Tumbling reminded me of this at their Helsinki coaches conference. It’s a simple thing that will make your stunts more aware of their movement, allowing them to fix it on their own.