The thing that’s always bugged me about SSAO is the “jitter” visible when the player character or camera moves, which I would imagine is due to it being calculated in screen space. In some cases it’s so distracting it breaks immersion.

Given that accuracy isn’t the goal anyway I’ve often wondered if it wouldn’t be better in many cases to apply a sort of pre-calculated AO that uses a relatively small atlas of shading textures rendered on flat surfaces as decals (disclaimer: I am not a graphics programmer). It’d apply only to angular surfaces (so for example human faces wouldn’t be included) but I’d say that 80-90% of the benefit of AO lies in things like corners of rooms anyway — it’s really just manmade objects that look bad without AO, organic shapes don’t suffer nearly as badly.