[dlam]

PP4 always essential. Even if it's not active, it is a monitor especially for alignment and ball position.
PP4 and PP2 I concentrate on when drag loading. I drag load my woods. If I'm playing well I try to add some drive unloading with PP1

For the irons I focus on PP4 and PP3. It's not a drag/drive loading motion. Rather I feel like I'm pushing/pulling the club.