Bidding Design Projects

How often, as a designer, find yourself creating an eloborate project schedule and bid, only to find you pretty much throw it out the window as soon as the project starts. Take a website project for example. In the past I listed each page as a work item in the schedule, allowing for more time to get the most important pages designed. There are several problems with this method.

1. Finishing the project and getting paid is now tied to finishing the project. Which, is generally completely in the hands of the client. The longer a project drags on the more I end up working to try to get things locked down.

2. I am always suprised by what sections of the site take the longest. In general clients don't really know what they actually want out of a website until they can see something close to finished. These unforseen trouble areas are can eat up the budget.