This post (before reading your comment) actually made me look into my own freshrss setup.

NixOS defaults to refresh frequency of every 5 minutes[0] (0_0).

I had noticed some blogs blackholing me before, but never quite made the connection.

So now it is configured to fetch every 12 hours. I believe that is fair.

[0] https://github.com/NixOS/nixpkgs/blob/d70bd19e0a38ad4790d391...