High school coaches adapt programs from college coaches, who mimic programs followed professional athletes. Many coaches, athletes, and other individuals incorporate program philosophies popularized in the '70s and '80s. These programs worked during the era when anabolic steroids were commonly used by many advanced weight lifters. Since then, anabolic steroids have been deemed illicit. With out these ergogenic aids, the programs of the past often lead to physical and psychological overtraining.
Training naturally is quite different than training synthetically.
A second set seems understandable since a warm up set may allow greater intensity for the the following workout set. Although, many of these studies have been criticized for using untrained subjects. Interestingly, a few maverick fitness authorities and professional bodybuilders have advocated high intense, very low volume training. Author Jones, the founder of Nautilus and MedX weight training equipment, was one of the early pioneers of single set training. In the 1980s, Casey Viator, the youngest Mr. America and Mr. Olympia contestant, and Mike Mentzer, Mr. Universe and Mr. Olympia contestant, promoted the high intense, low volume training.