When you have a number of identical (or comparable) elements and they haven’t already been made into a component, it would be great to be able to:

1. Select each element individually (e.g., a banner within a series of mocked screens)
2. Add these selections into a pile/group within the left or right sidebar
3. Choose one “exemplar” to represent the group
4. Create & replace each selection in place within each frame/screen with a component created from the exemplar

(4) could leverage the same UI as Library updates, where you can review each new instance as compared to its current state before confirming its update.