Sometimes I feel the urge to go back and negotiate more favorable terms for me or my team. (I'm talking about features in a software system, not money.)
The client wants to implement something. Sometimes is better for us if they want fewer things. Maybe if we do some of them different will also save us time. My reaction is to always stand up, and try to change the client's mind.
That's not necessarily bad, but only when we are thinking about the final product, and not our own time. When I'm acting as the client, it really makes me mad having people trying to change my mind just because it's more convenient for them.
There's a huge difference in the conversation when you approach it from the product's perspective, and not your own self(ish) interest.
I'm teaching myself to suck it up and live up to the expectations that were put on me and my team. Unless I have a valid reason to change something, I'm pushing forward to deliver it all. I want to always shoot for more, not less.