The argument of this book comes down to a single trade.
You give up a percentage of a recovery. In exchange, someone advances the costs at their own risk, preserves the evidence before it is gone, keeps the collections calls off your credit while you treat, builds the damages record, argues the value in a demand the other side has to take seriously, negotiates the liens down before anything is disbursed, and absorbs the loss if the case fails.
Whether that trade is worth it depends entirely on whether there is room in your case for it to be worth it. In a case with real injuries and real treatment ahead, it consistently is. In a case with no injuries and a fair number already on the table, it may not be, and a firm that tells you so is giving you the most useful thing it has.
The deadlines are earlier than they look. Two years is the statute of limitations, not the plan, and the clock on a claim against a public entity runs far more quickly. Evidence has a shorter shelf life than either. The other side has been working on your file since the week of the crash.
None of that requires a decision today. It requires a conversation, and the conversation is free.