"Lawyers can double up their billable hours - wait in court with one client, work on a document for another - bill both."
Sure they can - its called fraud. Anyone can do it.
They could also rob banks and make a heck of a lot more money.
"I suspect some of them have a researcher working for $30 an hour, and they bill the client as if they were doing the work, for $200."
Hmm. Once again, certainly could happen, also called fraud. (And if you know of someone who would be willing to perform legal research for only $30 and hour, please let me know.)
Actually, in most cases, the researchers (often called "associates"), do the work at a lower hourly rate than the partner in order to save the client money. Funny how that works.
Sure they can - its called fraud. Anyone can do it.
If the first client has agreed to pay the lawyer for time spent waiting in court, and the second client has agreed to pay the lawyer for time spent working on the document, how is it fraud? Both clients get exactly what they paid for. Neither is overcharged. The lawyer is compensated well.
Efficiency is not fraud.
Or looking at it a little differently, accepting your premise, which client should get the free legal work?
If I have room in my airplane for two passengers and each is willing to pay me $1,000 to fly him to Los Angeles, must I only charge $500 a piece if I take both?