My strategy is to have manual approval of the first few posts to filter out spam and other low quality content. All of the other limits like character count and entropy and all this other junk gets in the way of people engaging with the site so it’s turned off (or turned to an extremely tolerant threshold at least)
So far we have caught 100% of spam and no user has to suffer through a vague message about how their post needs more characters (which ironically probably promotes spam. Because to get around the message the simplest way is just to add character noise until you pass the threshold)