For me, I treat SB dates no differently than I would plain vanilla dates, and I also follow the 30 minute general rule of thumb, although there can be extenuating circumstances, particularly two: (1) she's in regular communication about her delay, and/or (2) she's really hot.
To improve your odds of not getting stood up, I find that it's important to have some contact the night before (via text preferably, and with a little sly innuendo if it can be worked in naturally), then also a follow up text a couple hours beforehand. If they don't respond to either of those, you should make other plans. For the questionable ones, I generally try to pick a nice, new place I'd be happy checking out on my own, so the night isn't a total loss if she doesn't show.
So many of these girls are flakes, so if you're not getting stood up occasionally, you're probably not setting the bar high enough. But I agree with the other poster, if she does show up significantly late, don't let her get away with it without suitable ribbing (it will pay off). And if you get stood up, do not, under any circumstances, respond to half-apologies later - if you still really want her, make her put forth the effort to come to you, at your convenience, on your terms