I got into bodybuilding when I was 19-20. (Turned out I was an easy gainer) I over trained and got injured doing Franco Columbu's Winning Bodybuilding. Nobody heard of steroids in those days (1976). I guessed that's why Franco could handle the volume better than a natural like myself. I had to layoff for a year. When I got back to lifting I began reading Mike Mentzer's High Intensity Training (HIT) stuff. I had really good results with it. A workout week consisted of about 40 minutes four days per week. The body workout was split. I still over trained if I wasn't careful.
Then a friend and I did Ellington Darden's High Intensity Bodybuilding. Mentzer and Darden were from the Author Jones camp. So is Dr Doug McGuff. Anyway, the two of use worked out on a very high intensity, full-body workout 3 days per week. We got the workout down to 40 minutes. Before then, I didn't think it was possible but I gained 2lbs of muscle per week over a period of about 6 weeks. My body weight went from 202lb to 216lbs. My friend, being taller, gained more muscle than I did. There was no special diet. I was in my late 20s at the time. Even though I was only bench pressing 1 set per workout (3 sets total in a week) I finally got over the 300lb mark as my best bench. A the end of those 6 weeks we were shot and fatigued. We had to lay off.
I get into my late 40 (circa 47 years old) and cut back to lifting once a week per body part. I was working out chest, shoulders, triceps on Monday, Legs and abs on Wednesday, and Back and biceps on Friday. My bench press went to 365lbs. I was warming up with 300lbs. I can't tell you about squats or deadlifts since I don't max them. Goes back to the low-back, overtraining injury I got at 19-20 from doing Franco's high volume training.
About that same time Mike Mentzer was doing personal training and keeping detailed records of his clients. Some of them weren't gaining. He thought they were putting enough intensity into the workouts and they were recording their diets. The only thing he thought he could tweak was rest. So he added days between workouts and his clients began gaining. Doug McGuff follows that same format and relies upon more recent university experiments.
I basically follow the same format as Body by Science but will do more than the five exercises he recommends and I will often do more days per week. If you are doing BbS I don't see anything wrong with lifting two days in a row and then taking the required days off to recover. I mix things up. I like to do 30 minutes of P90x but sub weightlifting for some of the bodyweight exercises .