It is a common misconception that in golf or other sports one must concentrate hard to achieve optimal performance. Think back to when you played at your very best - either a drive, or a long putt for example. The most common response when someone is asked what they were thinking was 'nothing'. If you have ever been 'in the zone' you will know that is the absence of thought or anxiety that 'gets' you in the zone.
This is why I firmly believe that clear keys are the simplest way to achieve optimal performance on a consistent basis. A clear key should be unrelated to the matter in hand so there should be no instructional aspect to it at all because it gives the concious mind an opportunity to try and steal control.
i've played some ok golf thinking of nothing much & also plenty of rubbish, & i've played some ok golf when grinding like a madman & also plenty of rubbish. I think concentrating hard is preferable to trusting the subconscious for all but the elite. If we have become intensely familiar with a good sound swing motion then we might be able to go auto pilot, but the challenge to my mind is that most of us don't have sound technique & don't know our motions well enough & so concentrating hard becomes thinking about one or two elements of the motion & hoping the rest falls into place, sometimes it does & more often not, but the poor result is not necessarily the fault of the focus.
how we focus might be important, to my mind visualisation is probably the big skill to do with high quality focus & is something that can be worked on & improved, visualisation is subtle & fluid & may be the best way for the conscious mind to direct the subconscious ?