There are only 12 Anomalies, 2 Digsites, and 3 Planetary Features per Storm type(Electric have 4, and Gravity have 5) all of which are unique. You can get just about all of them from a single Storm, you don't really need to do any sling-shotting of Storms to find them all passively.
The Features are also meant to be unique, but the flag is per Empire and they can spawn on uncolonized worlds within or without your Empire in spite of this restriction(at least the ones that don't require an event).
Ah, I didn't realise the features were unique - that's pretty disappointing actually...
Well then I guess amend my previous comments to "they should add a few non-unique generic ones and then make the deposits, anomalies, dig sites etc. you get when a storm leaves a system instead happen while the storm is there."
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