Maybe it's a terminology thing. To me, a retainer is just the amount of money you pay upfront to retain the services of the lawyer, and it does not cover the entire anticipated fee of the lawyers' services.
If you go through a trial with a personal lawyer for anything more complicated than, say, a DUI, you would be lucky to only spend $10,000 no matter how short the trial is, but either way the balance of the bill would be due either during the course of the trial to cover expenses or after the trial once all matters have settled.
