There were several instances where the only thing in the sidebar is the community rules only, no instance rules. At least one instance had rules in post that I don't think was even stickied in their main instance community or something stupid like that.

I don't bother reading the rules, because in the vast majority of cases they are vague enough to be uninformative (be nice!) or are so ridiculous that I'd rather just catch a ban than actively read every single rule everywhere to avoid tripping over one stupid community/instance specific rule. The only bans I've received across multiple accounts is either due to being a complete asshole (deserved), arguing with a stupid mod, or being banned for something the mod made up in their head to justify banning anyone who down voted a single post in one of their shitty AI slop communities.