I prefer my tarps in even sizes such as my 10' x 10'. I find I can configure it much easier and have more flexibility with various designs. I believe the even sized tarps give me more options and the worse the weather the lower the profile which means I can go from a Whelan design w/wo a fire in nicer weather to a Bombproof in nasty/windy weather with a reflective fire.
I personally do not like working with the odd/even tarps although I own one and use it in the summer months only.
My Spring/Fall 10'x10' Tarp in a Whelan Design -front view
Back View
This eVent ID odd size/shape tarp stays in my day pack during the summer only. This is a military Hooch design used in hot weather or in jungle applications. You can sleep but still see 270 plus degrees out. When used in the military a fox hole is created next to it so you roll out and into a fighting position. But most of your already knew that.
This is my winter 10' x 10' tarp folded up. It has sewn loops on all corners plus one on the center outside and center inside. It is my understanding it is material used to make Hot Air Balloons. Black material on outside and a subdued yet reflective heat reflective material on the inside. The only downside to this is it isn't the lightest tarp I own. Everything is a trade off. I prefer the waterproof wind resistant warmth of this tarp in the winter time over the ultra lightweights. But in the summer switch over to the lighterweight tarps in spring.
The Black on the outside (to absorb the sun rays for warmth) and has a reflective lining on the inside like a space blanket to direct heat down to me. It is amazing!
Look closely on this newer tarp shelter and you'll notice the tie downs are multi stitched AND they are sewn at least four inches up the side of the tarp. I've slept in this tarp in over 40 MPH winds in a white out blizzard and not one stitch or loop pulled lose. This is one rugged piece of gear!
All of my tarps except for the ID Silnylon can be around fire...one of the many reasons I like tarps is I can have a warming reflecive fire shooting heat into my tarp shelter when damp/cold/wet. Silnylon cannot be anywhere near flames/sparks. So I reserve it for summer carry at lower elevations only.