Lawyers bill by the hour, that's right. However there is almost always a race against time. You can always do the work slower/write more hours. But you can't speed up the work, if you don't have the tools.

In large offices, IMHO people get billed with their capacity to pay. It has not much to do with the hours lawyers put in. If the client has the money, lawyers put in more hours. Every piece of paper lawyers print gets billed to you. Every cab fare, every x and y, you imagine. On top of all this lawyers need to bill hours so they don't get fired. But I'd rather bill hours doing serious research than manual labor.