I took an American Red Cross Advanced Lifesaving course in 1988 at the age of 20 while in college. We learned to perform lifeguard rescues without equipment. Every lifeguard course I did after that was completely reliant upon the use of a rescue can or rescue tube. The YMCA and the Red Cross dropped their swimming standards over the years, but I figured the 500-yards in 10 minutes standard I did in 1988 was something to retain throughout my lifeguard and scuba instructor life.
19 years later in 2007 at age 39, I heard a guy yell for help at a beach. I ran from a space on the road about 100 yards down the beach, swam about 150 yards out, then put him in a cross-chest carry and began towing him back. I discovered I was in a rip and adjusted by swimming parallel to shore. When we got into shallow water, he wanted to hang out a while before we got out to save his dignity. He had become exhausted and had put his ego aside to keep from drowning. I told him that was smart. That kicked my butt!!! I was in truly great shape at the time.
Principle of primacy: The things you learn first you retain the longest. Almost 20 years later, that 1 credit physical education class became the most valuable course I took in college.
Having done the real thing on more than one occasion, I'd recommend a minimum fitness standard for USLA lifeguards for lifeguards, and the standards for USCG AST rescue swimmers or US Navy AIRR rescue swimmers for divers.