Many of my customers like to use them.
When I first started LA quilting, I was advised not to use sheets (shrugs). Without really knowing why, I use to say no sheets. Over the years I got braver & found there's no issue using sheets from the LA stand point (as long as it's been squared up lol)
I get all kinds of stuff. So far the most chllenging to work with has been pieced jeans (w/manufacturer seams still included) and minky (it's very stretchy). But most things are possible w/extra time and care. Of course if it takes extra time & care, it would stand to reason you may be charged more :)