What would be the advantages and disadvantages of spending two solitary years in a natural setting, like Thoreau did in "Walden"?

Rudyard Kipling's poem "If" reflects upon the need for a balance in one's life, attachment with detachment, righteousness without self-righteousness, etc.  So, too, does Thoreau suggest a balance in one's life when he writes in "Walden,"

I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach.... I left the woods for as good a reason as I went there.  Perhaps it seemed to me that I had several more lives to live, and could not spare any more time for that one.  It is remarkable how easily and insensibly we fall into a particular route, and make a beaten track for ouselves.

So, to spend two solitary years in a natural setting seems a bit beyond moderation.  Yet, some time alone away from the "world [that] is too much with us" as Wordsworth wrote, would probably be good for most people's souls.  Certainly, communicating with Nature and with one's inner self is always healthy.  Retreats by religious groups have been in existence for many, many years and people have reported feeling refreshed and renewed in their faith and in their inner strength.

Time spent alone in a peaceful, natural setting is time rewarded by beauty and spiritual reflection.  Yet, as Robert Frost writes, many people "have miles to go before... sleep." Individuals do have personal obligations to family and others that prevent them from contemplating beauty and communicating with oneself.  Added to this, people tend to fall into the monotony of which Thoreau speaks--the beaten path blinds people to much that is around them.  And, so, people must return from Nature for the same reasons that they retreat to Nature.