Now, we are making some more assumptions here. Assuming that after your wc claim was denied, you retained an attorney and are suing to appeal this denial. There were depositions taken in May of this year. You ask if "they" are lagging because they have no defense, as if you were suing the employer directly. You are suing them, but the carrier of worker's comp for the company is the entity who will be defending the case. Each state is a little different. Some have their own worker's comp court system. I'm sure someone on here will know more about CA specifically.
Just a very cautious guess here...of course you can always check with your attorney...but in many states, the urgency of the case is sometimes considered in the amount of time it takes to schedule it to be heard in court. And six months isn't a very long time to be out ahead of your court date in my experience. In some cases, it's 18 months to two years before the case is heard. I am not really familiar with CA, know that they do have quite a generous state disability program, not sure how this works in with the speed of getting the worker's comp claims to trial.
If there's any chance you will be ready to begin looking for other work soon, if you may have recovered from your stress enough to get back into the labor force, it is usually a good idea to file for unemployment insurance quickly when off work due to a disability issue. In this case where you have quit the job rather than be discharged for health reasons, there's even less a chance you will be approved, but even so, the claim needs to be set up by your filing for it, and you might be approved, you have nothing to lose by applying...or enough time will pass that you have absolutely no wages to set up an unemployment claim when you are ready to begin looking for other work, regardless of whether they determine you left your job due to a good work related reason and approve the reason.