People generally have a concern and a story, both of which need to be aired before the solution can be created and executed. I have seen a minimum consultation fee (think Groupon price for 90 min) effectively used for an organized and fully documented briefing at the first meeting. In this way the client is already on the clock and a majority of what you need to work with is already in your files. How many of us have felt guilty for a 15 minute overrun on the consult and then spent 10 minute chunks many times during the project looking for the email or phone or birth date? The longer initial consult leaves you organized and ready to execute more efficiently and saves you money in nonproductive hours you have to eat anyway.