A good user experience is very important to me in sites and products I design. However a good user experience doesn’t come by itself.
For every new project I start I walk through a user experience design process where I use mind maps to flesh out how the user will interact with the site. Then I let people use the site and product (as a ‘beta’ release) and provide feedback and use their feedback to refine the design. Ultimately (after several iterations) I end up with a product that is intuitive and easy to use.
With AutoCarLog I didn’t have the luxury of going through a heap of user testing, but I still felt that spending time designing it was worth while.
As I was doing the development, a model will increase my development efficiency. If you’re using a third party, then a user model will help them understand what you want. In both cases decreasing the time taken and reducing the cost of development.