I think most of us have watched a lot of his shows and know that he does use lean-to's. Though quite often his emphasis is on fire and radiant heat and dead fall shelters or teepee type structures. He also huddles into caves or builds rock walls to block wind and create a heat area.

When he does build shelters he, in my mind, he is mostly doing deadfall shelter, Les is very much a LNT kind of guy. I don't recall many shelters that have exposed sides like a classic lean to.

Thats just my interpretation of watching his show. I will be interested in seeing the responses for that statement from people who have read the book.