The guide text should be displayed when a new dashboard is created, but not when adding additional tabs.
The text is displayed for every tab a user opens.

Add a tab to an existing dashboard
I would also think about pre-adding 1 aggregation widget upon a new tab creation. Can not really see a use case where you would create a tab, and not add a widget.
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I would also think about pre-adding 1 aggregation widget upon a new tab creation. Can not really see a use case where you would create a tab, and not add a widget.