Would also depend on the content or topic of post.

Longer form probably 1 post every 2-3 hours or people might get overwhelmed and think of it like spam.

1 post every 30min-1Hr better be short to the point, maybe some good memes, directed as a quick dopamine hit. Would be time consuming for content creator.

1 post every 15 minutes should straight up be left up to bots.