While using how-to documents for guidance in performing computer-based tasks, users often run into problems due to inaccurate, out-of-date and incomplete documentation. These problems are often due to current documentation practices, which fail to keep how-to documents current, accurate, and complete. We believe that automated support for incremental update of how-to-documents, through the use of programming by demonstration and guided walkthrough techniques, is more effective than existing practice and produces documents that cause fewer problems for their users. In this paper, we present a study that evaluates this belief by comparing DocWizards, a tool utilizing these techniques, with a standard word processor. We show that more effective and efficient documentation can be generated by multiple authors using DocWizards in an incremental process, with effort comparable to that incurred using a traditional tool.