I think it only lasts a month, or a did when I tried it, but that was years ago.
Whether you use the maximum stop loss depends. If you are day trading something that isn't gapping much like forex, and closing your positions out end of day, then you don't need to pay that extra spread, it is a rip off imo. If you are holding over the weekend, or you're trading shares so that the likelihood of a gap is high, then yeah I think they can be useful.