You're both missing the point. What you said would apply to you as a personal trainer. Mike Mentzer was famous in the bodybuilding community. He probably had more clients than he could deal with. People that followed him also thought anything he said was gospel regarding training. Look at the crap he came out with toward the end of his life. Something like 5 exercises for one set every 5 to 7 plus days in his books.
He won Weider's version of the Mr. America training three days a week using a whole body routine. So everything got hit three days a week. From there he went to a 4 day week routine where he split the body in this manner. One day was Legs, chest and triceps. The next was back, delts and biceps. He trained two days in a row then he took a day off then train two days in a row followed by two days off. He didn't strictly follow the calendar and if felt he needed more time off he would take it. He used this routine to compete and lose in two Mr. Universe contests. Around this time Frank Calta was making a lot of buzz with his Rotation for Recuperation routine. That's around the time Mike Mentzer changed his routine to three days a week again. He didn't strictly adhere to days of the week taking days off as needed but he generally worked out like Calta doing this Monday: legs, chest and tricep. Tuesday:off. Wednesday: Back, delt and bicep. Thursday: Off, Friday: He was back to legs, chest and Tricep. He then took two day off. Now the next cycle it was reversed. Monday was Back, delt and bicep. Tuesday off. Wednesday was now Thighs, chest and tricep. Thursday was off. Friday was Back, delt and bicep. So body parts were hit twice one week or once a week in a rotation.
He generally used two work sets and exercise and sometimes one.
Only after he retired did he talk about using single sets and a very limited amount of exercises every 5 to 7 plus days. That's when he was training clients.
For clarity and cliff notes. Using days of the week for clarity. He didn't adhere to days of the week. Meaning he could have started his workout on Tuesday instead of Monday.
He won the Weider Mr. America using this three days a week.
Monday: legs-back-chest-delt-tricep-bicep-abs
Wednesday: Same
Friday: Same
Weekends off
________________________ ________________________ ______________
From using the whole body routine he went to this split.
Monday: legs-chest-triceps
Tuesday: back-delt-biceps
Wednesday: Off
Thursday: legs-chest-triceps
Friday: back-delt-biceps
Weekends off.
________________________ ________________________ ____________
Under the influence of Frank Calta he went to this rotation that got him into his best shape.
Monday: legs-chest-triceps
Tuesday: Off
Wednesday: back-delt-bicep
Thursday: Off
Friday: legs-chest-tricep
Next week he rotated.
Monday: back-delt-bicep
Tuesday: off
Wednesday: legs-chest-tricep
Thursday: off
Friday: Back-delt-bicep
Weekends off
This a sample of his thigh routine during his best shape. No warm ups listed.
Leg extensions were done pre exhaust style with the leg press as a superset.
leg extensions 2 x 12
leg press 2 x 12
squats 1 x 8
leg curls 2 x 10