Hard-Headed adjective
Used to describe someone who is realistic and determined
We must be hard-headed about what we are doing to pursue that goal.
She is a hard-headed woman that never allows emotions to affect her actions.
That hard-headed guy will never listen to my advice.
Be extremely stubborn
Used when there are too many people involved in a task, and this can lead to a failure or its likely outcome isn't good
I think five people should be enough in our project. You know, too many cooks spoil the broth.