That can be the goal. In my last experiment with this short of going to pure fixed bid, we had a client running an Excel spreadsheets to figure out exactly what

That can be the goal. In my last experiment with this short of going to pure fixed bid, we had a client running an Excel spreadsheets to figure out exactly what they were paying for hour, for each developer even. We finally just gave up and switched them to a pre-paid hourly rate per developer on the followup projects. Some other clients are happy with a retainer that gets them a certain level of work without sweating the hours. It may just be a shortcoming of the approach that my company tried; we're open for trying again as none of us like clocking time like lawyers.