During my past BizTalk engagements, I have had the opportunity to work closely with my clients in developing flexible and maintainable applications.  One of the most common issues that I come across is the misuse of some of the shapes available within the Orchestration Designer.  By misuse, I simply mean to say that many BizTalk developers will drag and drop shapes into an orchestration to implement the business process, but do not take into account the implications of doing so.  More often than not, the result of selecting the wrong shape for the job is not seen until the application is tested or even worse, the production environment.  One of the primary reasons that BizTalk is used is the opportunity to build loosely coupled, flexible and scalable applications.  By choosing the wrong shape, many developers will wind up doing exactly the opposite, thus setting the application down the course of tight coupling and brittle implementation.