I'd expect the MINIMUM duration for any ban to be a week. I've banned people anywhere from a week, to a month, to a couple of months, to a few indefinite bans that are still in effect.
The best way for any ban to get lifted, in my opinion, is to demonstrate that you have learned your lesson. Which, in your case, would require not posting a string of pointless messages everywhere at the drop of a hat.
____________"May the Grace of Ara go with you, and His Vengeance be wrought upon your enemies."
Only fools and children dream of heroes.