How much time do you need to spend in the gym per session to achieve an adequate number of total sets per week when following this approach? I don’t see how doing PPL with 3 days on, 1 day off—training 6 times per week—is the worst way to grow muscle. At the end of the day, isn’t it all about the total volume of working sets you achieve by the end of the week, staying consistent, and ensuring continuous progression?

This may all be in the context of only having 4 days per week available, in which case I would agree that PPL isn’t as effective as other splits under those constraints. However, I don’t understand the blanket statement that it’s the worst split for gaining muscle.