Greetings, all. The recent coupler thread got me thinking about the under-roadbed magnets used to uncouple cars in a yard. Well - I'm just about the finish the yard on my layout. One more round of "pull the track up and put it back down", this time adding the power leads. So this is the last convenient time I have to make any modifications, which brings me around to these questions: Is it worth the effort to put magnets below the track in the yard to help with uncoupling cars? What is the best location for the magnets? Do they need to be at the entrance to each final lead, or could one serve at the entrance to a bunch of leads that splay out from there? Are there any preferred brands or configurations for the magnets? Could I get away with some toroidal (doughnut-shaped) magnets I have just lying around? Any caveats? Thanks for all advice. I guess I need to decide on this before laying the track down for the last time (barring any mechanical problems).