Happy New Year! During the holidays are the busiest time for table runner sales. I often get asked about size of a runner for a certain size table. Many people do not know what table size they have. A good rule of thumb is usually you want the table runner to run over the side of each end about 10" to 14". Some people are now placing a table runner perpendicular instead of parallel.
There are many ways to lay a table runner as you can see in the above pictures. So don't get trapped in a box. Also if a table runner is too long for your table just fold it in half.
Here is a great article on table runners. https://www.wayfair.com/ideas-and-advice/how-to-choose-a-dining-table-size-S4891.html