Yes, it always happens -- which is why large corporations are successfully reducing fees where litigation is routine. Refusing to give any account of the time

Yes, it always happens -- which is why large corporations are successfully reducing fees where litigation is routine. Refusing to give any account of the time spent on the matter would probably get the lawyer disbarred. There's a legal duty to give the client an accounting of your fee, and the basis of that fee, so as to show the fee was "reasonable." And a key metric for reasonableness is the time spent. In failing to account for the time, you would be unable to prove the fee is reasonable -- and the lawyer has no right to keep a fee unless it is reasonable. You might try to get the client to agree in advance that $5m is reasonable, and to waive any right to you supplying an accounting of your time spent. But I suspect the courts would refuse to enforce that agreement, and the relevant Bar would sanction the lawyer and/or his firm.