This value, in minutes, is the configured or actual length of the collection window for a cumulative counter with no fixed interval boundary, running since the element or counter was created. On this element it is what you divide the accompanying access-hit byte and frame counters by to turn a raw cumulative count into a meaningful average rate for its entire tracked lifetime, and it is also how you spot a truncated bin -- one whose Duration reads less than the table's normal interval because a clear or restart cut it short. Because this is a AllTime bin without a fixed interval boundary, this field is most useful for confirming how long the counter has actually been running before treating its access-hit total as representative of typical behavior.