Here is my system for uncoupling, I have 27 on my small 22" x 13' layout, one at each position that I would want to spot a car at or break a train at. 

Moderator note: Changed to embedded YouTube video.

Thought I would share my layout. It is code 70 with under track magnate uncoulpers. The grain elevator goes where the black spot is in the upper right, you can see where the foundation for the loading shed is there. I combined the loading track and the lead for the small yard... The run-a-round has nice straight sections for coupling. As you can see it can stand alone, but expansion possible...