Yes, DS is incredibly wilful. Even at daycare, where all the kids obediently participate in their group activities and story time, he will get up and go off and do his own thing often, ain't nothin' going to sway him!
Ive vw found a couple of things most effective. 1. I NEVER reneg on what I say, ie. if he doesn't listen/do as I ask and I say he can go to his room if he doesn't then he knows I will put him in his room if he doesn't do it. 2. I found/find counting is very effective. Ie. 'I'm going to count to 20...' And he is very responsive to this because he loves a challenge!
I have little patience so I've struggled with losing patience with him too but On the other hand DS is so wilful he'd walk all over me if I wasn't so business-like in my transactions with him when he is being difficult! I'm also incredibly loving so there's no reason why parents can't be both.
Also, these rough patches you talk about, these are growth spurts.... Difficult times that will pass. Growth spurts are hard on them and us, just know they will pass.