This is the tarp I used for many years:

It was made by the Gerry Company of the 1.9 oz PU coat 70D nylon that was common at the time, and was a completely flat tarp with beaks front and back. The beaks don't show in the photo, as they were kept rolled up when not being used to deflect rain or snow. When extended, they covered out to the point where the two guys converge on each side into one line that leads down to the stake point.
Pole sleeves were sewn on to the sides above the beaks to make a tunnel shape. The poles were stiff ALU at each end, with flexible fiberglass in the middle so the poles would form a more parabolic shape for a solo shelter about 4' wide. A floor was connected inside by mini snaps and came up inside about 3" on the sides. There was also insect netting that rolled down inside the beaks at the front and back.
Condensation was mostly along the sides, 6-12" above the floor, but with the 4' width, was not a problem.
The tarp was used year round, once on a X-C ski trip to Little Rock Pond on the Long Trail during the winter where the temp fell well below zero F. The above photo was taken on Mt Madison in the Whites in May going through the Presidentials. There was ice and deep snow everywhere below the tree line. We had to change our route back down due to the thigh-deep post-holing. After Mount Washington, we enjoyed watching some skiers tip over the lip above Tuckerman Ravine, but we couldn't see them plummet down because the drop-off was too steep for us to look over.
As you might guess, whether I stayed dry depended on how strong rain was, and from what direction it was blowing. But windwise, the structure never failed, and it never leaked. A number of times rain did blow in, usually at the head end, and I got soaked at that end before kind of scrunching up toward the other end.
Eventually, I got tired of getting wet in windy downpours, and moved to tents.