Although adequately answered, I wanted to highlight a key part of Jimmy's mindset:
When arriving in the office of Davis & Main, there is a switch labeled "DO NOT TURN OFF". The notice is taped in a way that you can't even flick the switch without intentionally removing the notice.
Jimmy flicks it anyway. Because that's who Jimmy is. He doesn't play by established rules. He goes with his gut and tries to do what he thinks is right.
The same happens with the commercial. There are key points where Jimmy could have talked to Cliff. At one point, it seemed obvious for him to do so. But he chose to not do it. Because he doesn't play by rules that he doesn't agree with.
And Jimmy did not agree with the rule that Cliff needed to sign off on Jimmy's hard work.
The entire Davis & Main chapter is there to showcase part of Jimmy's persona. He does his own thing not because it benefits him, but because he thinks it's right. Up until then, you could have argued that Jimmy cuts corners because it's easier or directly benefits him in any way. But he has clearly shot himself in the foot with how he behaved at Davis & Main, yet he does not regret it. Because he isn't in it for himself, he's in it for what he believes is right.
And that is a redeeming quality for Jimmy, and I think it encapsulates the essence of his character.
I also think Saul Goodman lacks this same trait of wanting to do the right thing. I expect the loss of this trait to be (part of the) key to Jimmy's transition into Saul Goodman. But this is just an estimation on my behalf, of course.