I should note, that I'm only playing other inexperienced guys... I'm definitely not saying I'm super awesome, just that I don't see Petitioners as being Glory farms.
I rarely attack models if I'm honest. I always play my objectives and ignore the other player. I leave my harder hiting stuff up front so I can res back to Inspired mode, Esepcially the Prince, who seems useless as normal. Petitioners I use t oblock charges, and keep one at back to sit on an objective with the Warden.
In my last game against Orruks, I didn't attack any of them, Only the Warden attacks their Leader twice, after he had charged in... So i knew I could remove before ed of turn and not have him inspired.
What I have found, is that most models have a hard time hitting and wounding without upgrades etc. So I tend to ignore them unless they are interfering with my own plans.
I have a small beginner tournament on Sunday, we shall see if my style of play works or not