I cross them just out of habit. Not that it does any good.
For the chains to cradle the trailer tongue the chains need to be shorter then the distance between the hitch ball and ground at ride height.
Just hook you chains up and lower you tongue all the way down and see what happens? Unless your chains are shorter than the ball distance your tongue will be on the ground.
The way a lot of people hook their brake wire up makes it worse. A lot of people on this site don't have their brakes come on unless the trailer brakes completely away from the TV. WRONG way to do it. If the trailer brakes come on at least you have a chance that the trailer won't slam the back of you TV.
Like I said; I just do it out of habit.