While I signed up a personal injury and workers comp client today, he talked about how long everything takes. And it does. There are a number of reasons for this.
First, in both PI and workers comp cases it is necessary for an individual to reach "maximum medical improvement" meaning: get as well as possible. This is so that the claim is settled AFTER all surgeries and major medical treatments are done. You wouldn't want to settle, need a surgery and have to pay for it out of pocket.
Second, there are many cases. Insurance companies are large and have entire departments devoted to claims.
Third, lawyers and theirs staffs are busy. Legal proceedings take quite a bit of time and are work intensive.
These aren't the only reasons, but they are some of them.