It's every 6 hours, I haven't touched it in a long time, but it only publishes to wss://nostr.wine/, so it may be because your client is not fetching its notes properly (i.e. outbox), or maybe you only get them when someone republishes them to other relays which may not happen consistently.

Also I didn't get a notification for this reply (probably because your client didn't send to my "read" relays), I saw it by accident now.