I think its usually a very pre-arranged time (like once a quarter shortly after the quarterly earnings since you cant know what's in the next quarterly earning if the previous one just happened).

Besides, are there really bad and good times for the company? Its not like the company itself is affected, just the stock holders. Management wants stock to go up because management usually owns stock. So screwing you would also screw themselves.

Last of all, if you dont like the blackout periods, you can just setup an arms length plan to bypass it https://www.investopedia.com/terms/r/rule-10b5-1.asp