I rarely use anything except fleece for my backings, but have on special occasion used a sheet. I frequently use sheets in piecing my tops, especially for borders and sashings; no seams!!!
I access my sheets at thrift stores so they are rarely new; call that prewashed. A twin sheet is at least 4 yrds. in my best estimation, and usually $2. Can't beat that price!!
I can't do hand sewing and my machines have never had a problem sewing any sheet. Sharp needles are good for quilting them, rather than the round point.
Whatever you use, make sure you are having fun!!!