It would be horrible to waste time (or money) developing something as intense as a course or book that turns out to not actually work for you or your audience. Developing worksheets, slides, and a script or bullet points of info for your workshop will help you figure out if the content works for you, of course, but actually presenting the information to your audience will allow you to get a real understanding of how it works for them. Was it too long? Too short? Too hard? Too confusing? Just right?