Of course, there is a subjective amount of thinking, but again as others have mentioned it is entirely relative to the type of shooting taking place.
If I am shooting documentary or photojournalism, stills and video, I am more watching rather than thinking, the decision has been made to be in a certain place at a certain time, the only thought that counts to me in this circumstance is how best to portray the story through framing, all the other stuff like apertures, , flash etc etc, should be second nature. It is the observing that is paramount in this situation (personally speaking) and consideration for those viewing the end results and empathy towards the subject matter.
On the other hand, I think a great deal about technical stuff, conceptual application of it, what if I was to shoot a model this way or shoot her that way, absolutely, I'd be a fool not to think about it. But these are very different circumstances.