it would be nice if the symbol timeline would be repeated in the main timeline.for example if the symbol time was extended beyond the one second as shown below.
You can add a timeline action at the end of your symbols timeline to restart the timeline. It won’t show in the parent’s Main Timeline, but it will repeat at export time.
Both technically - though you may need to manually set the duration on a movie export if you have an infinite loop (as we wouldn’t know when to stop a video export).