Okay, here's the thing about full body routines. I have no clue why he does 5 a week, but with three a week it is the most effective routine you can do as a beginner. This may sound off, but let's look at the math
If you're a beginner it only takes about 48 hours to recover from workout to workout (volume and intensity wise for the most part)
That would be a 3 day a week full body routine
52(weeks in a year) x3 = roughly 156 workouts in a year for every body part. This is more volume and more practice with the lifts than say a push pull legs split which may hit every body part two times a week
Which is roughly 104 workouts for every muscle group a year. This is only 2/3 the volume you will get with a full body routine (which you can sustain for over a year, I'd say it'd be effective for 1.5-2 years).
Now if you want to hit every body part just once a week, that is 1/3 the volume of a 3x a week full body split. Only 52 work outs per body part per week.
As a beginner that is extremely unnecessary, as your recovery time is so short.
Also in regards to the only about an hour in the gym thing, as a beginner you also need less volume to make gains. Strength and size both. And the longer you lift, the more and more volume you will have to get per workout for it to be effective. So doing maybe 5x5, 4x8, 5x3 etc of the big 3 and minimal accessory work as a full body split is actually optimal for you.
Remember, just because people that are advanced do it one way, that doesn't necessarily mean it's best for you. The position you are in is greatly different and should be treated as so