In timelines, at segment breaks, people sometimes need the same behavior as in the board, when you extend the same segment on multiple columns : the underlying media does not stop. It could be called Free run mode. The main difference with the copy mode, is that it is applied on specific files and not on all the layers of the timeline. You would never encounter cases where your cue is delayed (wait mode) or hidden (copy mode) by pending media : you just have a media running, where you have a media-container on the timeline.
Moreover, if you allow each media independantly to be in loop mode at the same time as being in free run mode, you can have different layers looping at different paces, like the waves of the sea on a 62 frames loop, and the clouds in the sky on a 155 frames loop. (In the current version, we have single loop length, set with the segment length from the intro to the end)