I want to try to step out of my role for a moment and think about it from a user's perspective:
To me the button separation seems rather arbitrary in most current use-cases, that I've seen so far. If it's a multistep dialog/action connected, will the user understand that after using the green button several times and therefore finish his task more easily? If a multi-step action is needed, there's
common agreement, that
- possibly saving user's inputs at every step to be able to go back and forth,
- give feedback of where they are in the process and
- how many steps are left to accomplish the task.
Providing different button colors between the steps and providing one at the final step doesn't provide much feedback and it's hard to grasp without explaining it upfront and in-detail.
As we're already providing primary buttons and secondary ("neutral") buttons, I think we should consolidate the two different primary (progressive & constructive) ones in order to give user's a clearer focus on what's the primary action to get "bigger" tasks done.