When using warm 'n natural batting, do you normally use single or double thickness?

I use single, but I don't like heavy quilts and live it a hot climate.

Single thickness has always been enough for me!

I use the single for a more antique look to my quilts. It's a matter of personal preference but if you are planning to hand quilt, a thin batting is easier to work with and you'll get smaller stitches that way.

Single.

Single

Single

I use single layer.

I use single layer , but have been known to use a layer of Warm and Natural and a layer of low loft poly .. it gives more "Puff" to the quilting.. really does give a nice effect and it warmer.

I find it interesting that many people think a quilt must have a THICK, as in really puffy?, batting. Thick heavy quilts were not all that common across the country and were often made using yet another quilt - worn out and recycled - inside as the batting.
Of the THIRTY THOUSAND! quilts submitted to the World's Fair Century of Progress Expo in 1933, few if any quilts were in this style.

If you are not making quilts from old clothing, in very basic patterns, for the sole purpose of keeping your family warm on winter nights, then the "modern" take on the batting issue is generally cotton, thin, well quilted.
That does NOT negate the thick, big-pieced, tied/lightly quilted works, they ALL have their place.
Jan in VA