Common Sense vs. Common Practice

Our district began working with Robert Marzano's The Art and Science of Teaching" this year.  Several members of our staff are participating in The Art and Science Academy. As we learn more about the research and strategies it becomes apparent the much of this is not new.  In fact, we have known about many of these strategies for a long time and they are common sense strategies. However, during our recent cohort meeting it was stated that what is often common sense or common knowledge is not always common practice.  Why?  Are we bogged down with so much stuff that we simply forget the basics like setting learning goals or objectives? Did we forget that our students need to know and understand what those goals are? Establishing goals is just one thing that is common sense but often not common practice. Why? What are some others?