A quick look though a few GQ threads can show how a lawyer can have the ready answer to questions a layman might not necessarily know. As far as real world examples:
Say you have an outstanding warrant, and have had it for quite some time. You go to a lawyer to ask if the statute of limitations has run on it, a common question. The lawyer explains no, the statute of limitations only says that the state has a certain amount of time to file on you. An outstanding warrant means that you’ve been filed on. Still, he’ll see if there is something he can do. On reviewing your file, he notes that there’s a fundamental error in the complaint, something that someone who didn’t have some legal training or experience wouldn’t catch. The statute of limitations can’t prevent you from being prosecuted under this complaint, but it prevents the state from refiling on you if this one is no good, which it is. Your lawyer files a motion to quash the complaint and dismiss the charges. You walk.
A real life example: a kid came into my office a week or two ago with a minor in possession charge; his mother’s legal insurance gained as a state employee was footing the bill. He was charged with having a case of beer in his car even though an adult coworker he was driving home told the officer it belonged to him. I set it for a jury trial. The DA, seeing a misdemeanor that’s almost never contested set for trial, investigates the case. Realizing that it’s a dog, she dismisses the charges. The kid probably couldn’t have beat her in court even with a good case, but she knew I would. Being a good trial attorney is a surprisingly difficult skill, one which I have far from mastered. My dad is easily ten times the trial attorney I am. Knowing how to get in evidence, how to direct and cross examine effectively, how to choose your jury, how to get your point across to the jury, when to object, etc. etc. takes time to master. Sometimes it looks easy, but that’s just because a good lawyer makes it look easy.
Another real life example: A client of my dad’s is fighting not to have his parental rights terminated by the mother. We won in the trial court, but the mother’s attorney has appealed it all the way to the Texas Supreme Court alleging issues involving the statute of limitations, standing, and due course of law under the Texas Constitution. My dad doesn’t much care for appealte work, so he gives it to me. I recently completed a term as a law clerk to a federal judge, and pretty much my main task for 50-60 hours a week for a solid year was doing legal research and writing briefs and opinions, and an extremely high standard was demanded of my work. A research and write a reply brief that I’m pretty damn proud of, make and bind the dozen or so necessary copies, and mail 'em off before the due date. If the father had to try to figure out what to do by himself, i.e. how to research, what was relevant and what wasn’t, what cases supported him and what didn’t, how to write effectively, how to comply with the rules of court, and so on, it would have been virtually impossible to write even a crappy brief. It’s not that I’m any smarter than the father, I just have way, way more experience in this matter than he does.