Couldn't agree more with the main thrust that spending time to ingest the site, the surroundings and identify what parts of your own personal mental soup lights up is something personally worthwhile and does of course allow you to reach a deeper 'appreciation' of a site but I'm not sure about 'understanding'.
There is also the very likely possibility that you end up projecting the feelings and emotions evoked by what your senses are picking up back out onto the landscape in front of you, rather than an accurate reflection of what the site is 'about', 'for' or 'signifies'. An accurate reflection is most unlikely in our world apart from ancient times and in any case cannot be verfied in any meaningful way.
Thats not to say its in any way worthless, it is getting in touch with a possible primary motive of stone draggers but I think we may be too confident in our ability to 'download' information from the landscape rather than upload the emotions produced in our minds.
The mental projection of the mind triggered by the stimulus on the landscape is what I would consider to be the root of the 'sacred' place, the sacred is inside the human mind in my opinion and is invoked by triggers in the world around us, probably linked to the territorial nature of us wild humans. Our territorial nature most likely causes us to place significance on features in the landscape to define 'our space', the uniqueness of certain landscapes could trigger a universal response in the human psyche and it becomes a universally sacred landscape. I'm not sure that there's anything more inherently sacred in the rock, mud and life on Croagh Patrick than in the rock, mud and life covering a landfill. There are no sacred landfills but its not beyond the bounds of the human psyche.
Basically what I feel is that its good to connect with parts of our nature and label things that touch certain psychological nerves as 'sacred', 'beautiful', 'sexy', 'scary' but I think it gives us more information about the human mind rather than the stimuli the senses are picking up. Maybe its cold and cynical to take this view but I'm not in any way trying to lessen the feelings and emotions picked up and experienced, in fact its part of our nature we should all explore more but I dont think we can then say with our heads and our hearts with certainty that its inherent in and part of the landscape, no matter how much we wish it to be.