When should I stop my brain from going on auto-pilot mode? Auto-pilot mode is there for a reason. It is to prevent us from re-inventing the wheel. This is solely my understanding.

My question is how do I decide when to go on auto pilot mode and when not to?

Is auto-pilot mode always bad?
Never ever go on "auto-pilot", might it because diffuseness seems to be most unproblematic. That's "animal practice" and absence of mindfulness and investigation, does not lead to discerment and bear a lot of dangers.

When doing, experiencing, what ever phenomena arises: know, investigate, judge it.

As for actions (body, word, thoughts):


  The Lost Wallet
  
  It's as if you leave home and lose your wallet. It fell out of your pocket onto the road away back there, but as long as you don't realize what happened you're at ease — at ease because you don't yet know what this ease is for. It's for the sake of dis-ease at a later time. When you eventually see that you've really lost your money: That's when you feel dis-ease — when it's right in your face.
  
  The same holds true with our bad and good actions. The Buddha taught us to acquaint ourselves with these things. If we aren't acquainted with these things, we'll have no sense of right or wrong, good or bad.


A maybe good and helpful talk on this matter, also in regard of the other current question by same questioner, by you: 


  Seeds of Becoming , by Thanissaro Bhikkhu
  
  The author points out the place where we are able to lean to understand all issues which are moving this world. A Dhammatalk on Bhava (Becoming) and how we are able to transcendent birth, aging, sickness and death, exactly here and now.
  
  ...what happens a lot of times when people travel on a road day after day they start blanking out, actually stop noticing things. It's **like a person gets into a state of concentration and then just doesn't want to develop any discernment, just likes the blanking out, or the stillness, and just holds onto that and gets oblivious to other things, like the person who drives the road from the Valley Center to Escondido every day, after a while you just don't notice anything. It's where a lot of people are, their brains just go into automatic pilot...*


[Note: This is a gift of Dhamma and not meant for commercial purpose or other low wordily gains by means of trade and exchange.]