Indeed. It is really just tension x time under tension within a sensible rep range (probably around 5 - 30 reps or so). Menno on Youtube has a bunch of videos on this, the link below being the latest one.

https://www.youtube.com/watch?v=rmOBmTZARq8

Basically work the muscle harder and get more jacked. It isn't that hard. Full body workouts are also great for this reason: you can hit a muscle more times per week and be fresher when you hit that muscle, so both the tension and time under tension can be higher vs a body part split.

The reason for varying your workout I have heard is to avoid injury, not to be stronger. Of course it may turn out that is false too.

It doesn’t really affect hypertrophy but it matters because imbalances will get you weird injuries and/or mobility restrictions in the long term.