Some people do X's, some just attach it to the same side. IMO there's not "right" answer. I attatch it to the same side, personally. Some, like my show sheets, that have attachments like this have
to attached on the same side. With the "regular" type elastic straps though, it doesn't matter.
Haha.. and then of course there's the ones that go around the butt, like the Rambo blankets have.. I hate those! They just end up covered in poop. >___>