I set firefox to clear every time I close the window. I feel that is best practice.

My big concern is ad based malware, cache poisoning attacks, etc. I always use Firefox with ublock or Brave at min on those sites. Ironically we'll probably kill all the free ones doing it but maybe for the best they go away anyhow. Mostly stolen content and non-consensual uploads. Anyone who hangs just in Pornhub is a total normie at this point so I ain't even talking about Pornhub here. 🤣