I've noticed this since I had L4 and see this behavior in the current L5.
When I create one or more collections, these are selected by default in all my layouts that use the Cited By tool. I recall that, in the past, this behavior did not occur in an earlier version of L5 (sorry I don't recall which version).
Is this behavior by design? If so, what is the rationale? As my number of collections grow, and as I use more layouts with the Cited By tool, I end up spending more time unchecking new Collections in my layouts that use Cited By.
The Cited By is a great tool, but is also not scalable in terms of managing and organizing the growing number of Collections.
David