What it is: This notice indicates that there are one or more SmartTasks in this project whose duration is set to 30 days or more. The duration is the number of days given for the task to be completed.
Why it matters: When a task's duration extends out over such a long timeframe it can be hard to meaningfully monitor progress, thereby resulting in delays.
What's next: Whenever possible, break longer tasks down into smaller tasks. In the example above, the Final Testing task was 40 days long. It was possible to break this out into four smaller tasks, which totaled up to the 40 day duration, but allow us to monitor progress in a more granular way.