For small projects
such as writing a report, you as the analyst sometimes know that the client needs these fields not specified. If I'm sure I add them tho doesn't hurt to check with the customer to see if they need extra feature etc.
This is left out of the 'waterfall' or standard IT project methodology, as something undesireable, 'scope creep' but is incorporated in more flexible methodologies such as RUP or 'Rational Unified Process' where you have several iterations during construction, between inception, elaboration and before hand over of course.
This gives you 'opportunity' to 1) make the product meet the customers needs better 2) be more sure that it meets their needs early, when change costs less, by involving the customer in early prototypes, etc.
Your accounting needs to be flexible enuf to account for scope changes early. Later scope changes are less desireable.
