I could pass into the filtering script the age of the pubkey in the local database, or the number of events you have from them.  Either one would allow the script to notice this is a new pubkey and then your filter code can be more aggressive.

I should also pass into the script the phase of filtering (incoming? displaying thread replies?)

More work tbd I see. 

 good thinking 
i feel WoT block legit human npubs who post once an hour or day or week 

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