Comment 7 for bug 61530

I think the maximal safe length is 0 seconds as we can't really be certain that the shutdown action will take at least a certain amount of time. This might even be the reason that Apple decided to not include a shutdown sound since OS X shuts down very fast as well. The best route to take might be to create a very short sound, like a single chord / interval and have it fade out quickly. I'll try to get something like that produced quickly.