I was a lifeguard, so I can speak with some authority. Both skills are necessary. Not only do you have to count and track swimmers, but you have to keep mental notes about their abilities, be aware of what they're doing, and imagine possible outcomes so you can identify and react quickly to the actual outcomes. If your attention wanders for too long, especially at a busy place, you can easily lose track of someone. If you lose track of the wrong person, well, buckle up.

Fortunately, there are usually multiple lifeguards on duty with you, you're usually on a strict 10- or 15-minute rotation with them, and one of the stations is the break room. That helps a lot.

Lifeguarding at a camp is at least 5 times more difficult than at a pool, and I suspect that's why they ran drills to keep the lifeguards on their toes. Underwater visibility is usually next to nothing. The lake is usually full of teenage boys. Access to the water is effectively unlimited. There are often a lot of occluders, such as boats and bushy shores.

1) To keep counsellors attentive to the specific children under their care.

2) To give the lifeguard's the chance to practice their missing child search procedures.

It was stressful, and it was effective.