I've never used a built ground blind, tent or whatever. I've killed dozens of deer from the ground. I've used depressions, stream beds, ditches, blowdowns, fall downs all sorts of natural occurances for cover. This deer was taken at 12 yards this year sitting in a shallow ditch tucked back in some brush. The exit hole was higher than the entry hole.
My closest ground kill was anice buckat 7 measured FEET while hiding under an oak tree that was maybe 5 inches in diameter..