This is a nice little form from the Pennsylvania Workers' Compensation Bureau that describes the flow of the basic workers' compensation case. We have a printed version of this form in our lobby. It's a good summary of what's done and can be a good visual explanation of why these cases, sometimes, take a long time. Of course, every case is different so your particular case may not follow this example exactly.
You can find the form here.
You can also find a flow chart here that describes the claim documents that are most commonly seen in cases that are NOT in litigation. Just scroll over the document title for a description of what that form is used for.