If you tie the ankles next to each other, and you tie them tight, they press against each other on the bone, and this hurts. Moreover you are still able to move one ankle in front of the other, and then you have too much freedom.
Anyway it does not matter very much. Use your favorite method. It is also possible not to tie the ankles at all. Be careful using a spreader! I have no experience with this, but it could be very difficult to pick up the keys when your legs are spread, because you cannot lie on your side, and your hands cannot reach the ground.
If you want a hogtie, then it is better to use the second method on the drawing, so that it will be easier to reach the end of the chain, and the force is symmetric on both sides.
I use the following materials:
