When working on a software project for a client, there are two ways in which this can be billed - fixed fee project, or per hour billing.
Does the choice of payment terms effect the design methodology you would choose to use?
For example, one of the benefits of Agile programming is that changes can be made very quickly, and there is less emphasis on documentation, particularly with regards to design up front. This is great for per-hour billing, but when working on a fixed-fee project, you want to avoid changes as much as possible, or bill extra for the additional work created.
In such a case, documentation and initial design become more important, as they form a great way of agreeing the exact scope of the project, and can be used to show deviations from design and therefore extra charges.
Do you tend to use different design methodologies for fixed-fee and hourly rate projects? If so, what particular methodology do you feel works best for fixed-fee projects?