I think the spray is a mess, they're breathing it in, and it's going everywhere except the body.
Most people, kids as well as adults, use about 1/4 the amount of sunscreen they should. You really have to use a good ounce or two to get coverage. It does not good if it's still in the bottle or sprayed in the air.
My son's camps always had the kids use the body system, where they goofed each other up especially on the back, neck and shoulders, and with some slow, careful work around the face and ears.
I agree with Suz about doing too much for our kids - but we also have to tell them that not everything in life is instant like a smart phone with a good operating system. There is a value to a few minutes of concentration on any task.