It most certainly isn't healthy. However, it has been common in fitness circles historically, and this, I believe, is for two reasons: (1) bro science methods of training actually happen to work well if you are on steroids, but for a long time steroid use wasn't as well-known as it surely is now. Arnold would therefore advocate for such methods of training, and that would become the gym banter among "bros." (2) Personal trainers use it to exploit their clients, because they "feel" the burn --even though there is no relationship between the "feeling" of a workout (including "the burn") and its efficacy. How one feels about their regimen is a different matter --some principles will always apply, like lifting heavy, getting lots of rest, and eating real food, but schedules and life get in the way, such that training programs need to be adaptable. This is an extension of the general tendency in modern life to contribute as much output as is possible at the expense of quality --look around at most institutions or individuals producing things at a mass scale and one sees an almost causal relationship in the diminishment of quality from quantitative overload.