I have a client - one that's well trained after many years - with 25 rentals, in six different states.

His return can be keypunched directly from the organizer due to the training I've given him.  

His bill is less than it would be for a client that wasn't organized.

I've been know to actually add a line item to the invoice for disorganized clients; most of 'em have moved on as it's not behavior I tolerate.  And those that haven't pay a premium for me puttin' up with them.

As others have said, you have to bill what it's 'worth', and only you can determine what that is in your community.

If you are new to this profession, I'll offer a word of advice.   Don't start with low fees to attract clients - you will regret it.