I would have no problem with allowing for different time frames. Hell, I'd have no problem with everything being entirely case-by-case, but in this instance I think it's particularly helpful to have a standard guideline. Bans can lead to heated debates in staff, and requiring them to come up with a time limit for their appeal as well would be another hassle for every instance. It's probably best to have all bans last at least a set time, whether 6 months or a year.

There's no real point in having multiple options, because the staff is not obligated to unban anyone at anytime. So just because the period is, e.g., 6 months, doesn't mean more serious offenders have to be considered for unbanning then. It's for that reason that, if anything, the time requirement should err on the side of leniency. This gives the staff the maximum discretion to have lighter punishments for lighter offenses, while doing nothing to interfere with giving the douchebags a very long ban. So I really do support a 6 month ban.