Clients expect the work they plan to get done. They don't care about the hours you spend unless you demand they care about it, by running an hourly meter.
One thing I’ve always been curious about is why law firms so aggressively meter. Wouldn’t most arguments you’d apply to software consultants apply to them as well?
It's a good question, and I really believe the answer is just that they've been given social permission to gouge (at least, if you're not big or savvy enough to work out a fixed-fee arrangement) that other professions don't really have. Everyone expects a law firm to nickel-and-dime. And, of course, you're really wary of that when you take calls with your lawyer.
It's something they are expected to do for their clients, so within reasonable limits doing it to their clients is expected and shows a serious professional attitude.
For example a defense Attorney defending a DUI charge will likely be a flat fee. They will also charge according to what it is worth to you.
e.g. If you were Palo Alto's most successful real estate agent, and were at risk of losing your drivers license, you will be charged accordingly when you show up at the doorstep of a prominent defense Attorney.
^tptacek speaks wisdom here. If you have a client giving you a hard time about your time units, that's probably a client who will be more trouble than they are worth. When I was still doing consulting, I got to a point where I steered every client toward monthly retainer billing because I was tired of the ones who wanted to count every hour rather than focus on outcomes.
