Leave a margin of about three feet when passing a car least the driver pop their door open just at that time. Animals will, from time to time, wander onto the roadway and frequently get killed. Naturally you do not want to ride over the body. My scouts took particular delight in describing the grossness of the corpse. When crossing a road, some groups will use this call as each rider crosses.
People tend to rely too much on the rider ahead and just repeat the call without really looking .
It is better to train each scout to look both ways before crossing. If you do decide to use it, I suggest you have an older scout or adult ride ahead of the group, cross the road and stop where he or she has a clear view of both directions. Later you may want to go to each scout calling out as he crosses. Helmets are a controversial topic in some groups. You either hate them or you love them.