This is always misconstrued, he went 3 times a day, once at 5AM for one major muscle group, eat then nap for an hour or so, go back near the afternoon for the opposite major muscle group he worked on previously, eat then nap and some other stuff like PR/intereact with fans, and then go back to finish off the muscles and cardio. For him, it was a full time job to look good and grow...and the bigger you get, the more work it takes to maintain it, let alone grow even more.
Something serious to consider- he took steroids, and had been consistent with his training for YEARS before doing that. I've trained for 12 years, and I'd NEVER tell anyone who's worked out for less than 6 months to work out 3 times a day, let alone 2 times unless they are already pushing and pulling some SERIOUS weight (200+ pounds bench, 100+ pounds curling) and their results aren't as great as when they started.
I WOULD say if you DO do it, when I was consistent with workouts and did it "full time" (it IS a full time job to build muscle beyond 200 pounds), I did heavy weights with say arms in the morning/early afternoon to failure, then lightened the weight in the evening and focused on complete muscle failure with my arms. Next day, same thing with another muscle group...always making sure to refuel before going back to the gym (I was eating upwards of 4000 calories, mostly protein and good amount of carbs to avoid injury....nutrition is more important than the actual lifting).
You can also lift until complete failure on say, biceps early in the day, and then focus on triceps in the evening (basically doing compound sets for each routine, which can be just as effective).