If you are in a quick conversation with someone, you might feel the pressure to avoid any stretches in silence. Try to not feel pressured. Pausing for 15 seconds isn't feasible, but one or two seconds helps a lot...
It breaks your train of thought, allows you to catch enough things—doesn't have to be all—to formulate a measured response. If you want to go one step further, try not creating a response in advance and wait for your turn to speak. Instead, listen to what your conversation partner says and restate a quick summary in your own words before you advance the topic.
So true. At the same time, this happens because a lot of hiring managers don't know intimately what the job actually does, so they resort to cookie-cutter interview techniques.
Pro tip: Become Leonidas