It is wonderful to have a sheet sheet where the fitted sheet actually fits the mattress!  I had one other sheet set 15 years ago, that was percale and stayed on the mattress and it was getting very worn.  The percale keeps you from getting so hot when sleeping. I did wash it once before using it on the bed and the navy bled somewhat on the fabric softener cloth and I will have to wash it again to eliminate some more of the stiffness associated with the newness, but am very happy with the purchase.  The depth of my mattress is only 11" and the alround elastic keeps the whole fitted sheet completely tucked under.
I have found these sheets have not softened up and sometimes they seem too scratchy on my feet and legs.After many washings, I still find these sheets cool, but the wrinkles are awful.  Even when I take them immediately from dryer and put onto the bed and try to smooth them out.