Some cases settle relatively quickly, while some take years to settle. Oftentimes, there is no settlement at all after years of litigation and the case must be decided in court by either a judge or jury. The bottom line: there is no way to predict how long your case will take to resolve, assuming it even does resolve.
Here is a great article on why, and how, there are so many delays with personal injury cases, from the National Association of Personal Injury Lawyers wesbite:
"In this article, I will attempt to pin down the inherent causes of the anxiety and impatience some people feel when their personal injury case seems to drag on forever, with no clear resolution in site. Personal injury litigation can sometimes take years, with little hope in sight, at times, of seeing any substantial reward. But that's no reason to lose hope, as with a little perseverence and the law (and a good personal injury lawyer) on your side, justice isn' so far-fetched an idea after all.