The Default Duration properties define how long each item in the play list of your element will be displayed when no specific duration is assigned to individual items.
When data scrolling is enabled and you choose to Scroll using play list durations, this Default Duration will automatically determine how long each data row is displayed before scrolling to the next row.
The Default Duration ensures a consistent timing for items when individual durations are not specified.
If you manually define durations for specific play list items, those specific settings will override the default duration for those items.