Tavern question

Hello. I barely use the Tavern and somehow I almost forgot the game says "Tavern will refresh every 4 hours". I'm assuming that's just the free refresh.

However, sometimes it seems like every day, some generals pop up more often compared to others while some just don't really appear. Does it really matter which day I try to recruit generals to enhance current ones? Or is it always the same chances per general every time? I feel like I'm going insane.

How does the Tavern Recruiting even work?