It can definitely work. In fact I’ve been training my whole body every workout for the past 14 days (except for one day when I was traveling).
HOWEVER I believe that you do need a certain volume threshold at each workout to stimulate protein synthesis. So it’s not as simple as dividing the total number of weekly work sets into 6 rather than 3 workouts. It might not work.
Research leads me to believe that you need at least 3 work sets taken to failure for a muscle to stimulate a significant amount of growth in a workout. And I would say that 4-6 would be more “effective in real life”.
That’s why you can’t major on the minors when doing whole body training. I don’t like whole body routines where you have an exercise for every muscle… pecs, back, delts, traps, hamstrings, quads, biceps, triceps, abs, lower back (sometimes more since they divide back and delts in two). I prefer to use an approach with less exercises, covering everything with compound movements, and doing more sets for each exercise.
Pairing A (A1, A2): lower body
A1: quads focus
A2. posterior chain focus
Pairing B (B1, B2): push/pull with emphasis on push
B1. Pressing movement
B2. Biceps exercise
Pairing C (C1, C2): pull/push with emphasis on pull
C1. Pulling movement
C2. Triceps exercise
Then you can do abs
Depending on your tolerance for volume you would do 4-6 work sets of each, the last 1-2 being taken to failure or beyond.
You can change exercise every workout or have 2 or 3 sets of exercises or even keep the same exercises everyday.
This approach is best for a type 2B or 2A… type 1A and 1B would do better on a high frequency routine based on big lifts…
A. Squat variation
B. Press variation
C. Hinge variation
D. Pull variation