OK, so you have a really pressing need. The temptation to tell us so, in the hope to get answers faster, is big. So you put an "URGENT" into the subject line, ask for answers "ASAP", reask the question in the same thread or a new one, etc.
Well, here are reasons why this typically isn't a good idea at all:
We all answer questions here voluntarily, in our leisure time. We do that because doing so is fun for us, because we enjoy helping people and having interesting discussions.
Guess what, it is much less fun if it gets stressful. So the last thing you want to do to get us to answer your question is to pass your stress over to us.
People who are stressed and want a fast answer often don't even find the time to do the necessary research or to formulate their question in an easy to comprehend way. That's even less fun to work with.
So you really don't want us to feel your stress. Instead you want to take your time to write a well formulated post that is fun to answer. The less likely it is for us to know that your question is urgent, the more likely you are to get a fast answer!
The simple notion that you want your post to be answered faster than those of the other members might feel rather unfair to some of us. Doubly so because often "urgent" questions actually are homework questions. Yours might be different, but someone who had bad experiences with this type of question might not read far enough to notice.
If it is really that urgent, my answer may already come too late, so I will think twice before taking the time to formulate it.
If you asked the question once, everyone saw it. If they didn't answer it the first time, reposting the question isn't going to help, but will simply add more noise to the forum, detracting from the experience for others using the site.
Last but not least, having the word "urgent" in the subject line actually obfuscates it, makes it harder to decipher what the actual question is, and therefore to decide to actually read the thread. This grossly conflicts with the important practice to UseAMeaningfulSubjectLine.
So, please don't tell us that it's urgent - just tell us what your problem is, in the clearest way you can, and let us concentrate on solving your problem.
If your question hasn't been answered in a timely fashion, ask yourself: Is there something about the way I've presented my question that gives the impression that I'm not willing to ShowSomeEffort when asking it? Many people will skip by questions if the orignial poster wasn't willing to UseAMeaningfulSubjectLine. Many still will start reading your post and then get tired and leave without answering it if you didn't care enough to UseRealWords when typing it.