When Should We Let Other People Think For Us?

My initial response (reaction?) to this question is, "Never!!"  I want to do my own thinking, thank you  very much.  I believe I am pretty good at it.  But. . .

The wealth of data that human persons know, or have collected, is simply too rich.  Eric Schmidt said, at the Techonomy conference in Lake Tahoe, CA that 'Every two days now we create as much information as we did from the dawn of civilization up until  2003, according to Schmidt. That’s something like five exabytes of data, he says.'
I'm fairly smart.  You are fairly smart.  But that is simply too much data to absorb, correlate, and draw conclusions from.  So what thinking people tend to do is to specialize.  Jane might specialize in Information Technology, Brianna might specialize in internal medicine, and Ahmed might specialize in military history.  

But wait! as they say in infomercials.  Even in a specialty such as Information Technology one human brain cannot know it all.  Cannot know all the data, and cannot correlate even what it knows fast enough.  When I was an active IT professional I read 400 pages or more per week, and even then had to stay within a small slice of the field.  I stayed roughly within the slice that affected my professional duties.  Even with that limitation I believe I missed great hunks of information that could have helped me and my employers.
By reading extensively, attending a few conferences, what I was doing was paring down the input into what could be absorbed and relying on the thoughts and experiences of others.  Yes, I let others think for me.
I did, however, test their conclusions if something seemed to apply to our situation.  That's when thinking for myself kicked in. 

Was it enough?  No. 

I then passed it by various "stakeholders" in the employing for their thinking.  Well, not everybody actually thought.  There were knee-jerk reactions.  Prejudices played a part.  It was up to me to filter the responses as well as ask others to filter mine.  Eventually we made decisions that had some thought behind them.
Yes, others helped think for me.  I am not immune to knee-jerk reactions or prejudice or emotional dismissal of data.  No person is, in my experience.
We need others to help us think, and to help us think well.