Oh back in the day, when I was in the Boy Scouts (50's) we only had access to the old us military pup tents. Two of us would each carry one half of it and boy, made out of canvas, it was heavy. Leaked like a sieve, but it was top shelf back then. Over the years , I have had pop tents, mountain climbing tents and family wall tents. All better then any kind of lean to. I have on occasion made a couple of lean two's and although better then nothing, bad at best. While hiking up at lake tahoe with a friend in the early 60's, got caught in a out of nowhere snow storm. Lean to was better then nothing, but almost froze to death. Did keep is dry though.
Lean two's are last ditch, nothing else avail. type things. In my bob, I carry two person mylar emergancy "bags" and tube tents. Erected fast, keep you sorta dry, and the mylar double bags will certainly keep you warm. The real plus is that they weigh next to nothing., Condensation can be a problem though, so you need to try and keep a little air flowing though as best you can.
