Some companies like Microsoft were highly rigorous in managing information disclosure, and also in maintaining a lengthy quiet period. I could often hear investor relations at MSFT in the backgrounds of calls flipping through their internal playbooks of what they can and cannot say. Some other companies weren't as structured. I can't speak for how corporates managed disclosures internally, but I managed my own risk by typically publishing right after e.g. a corporate access event to reduce the risk of selective disclosure of material information.

I saw a handful of Reg FD filing updates and stock halts when new information was accidentally put out there by management. That was always embarrassing.