While the software developers endeavor to make things as simple as possible, businesses are necessarily complex and the software has to match that complexity. Every business is also different and the processes that work in one company, may not be appropriate for another. In ADempiere, almost all parts of the application can be customized. If you are working with an installed version of the software, its likely that the System Administrators and Integrators responsible for it have developed numerous customized workflows, processes, reports and what not. You will likely receive specialized training on these things.