In my experience, much more effectively and efficiently when the interaction is direct and factual, rather than emotionally padded with niceties.

Whenever I have the ability to choose who I work with, I always pick who I can be the most frank with, and who is the most direct with me. It's so nice when information can pass freely, without having to worry about hurting feelings. I accommodate emotional niceties for those who need it, but it measurably slows things down.

Related, I try to avoid working with people who embrace the time wasting, absolutely embarrassing, concept of "saving face".