The need for sound Instructional Design, and thus the impetus for treating it as a science, has much of its roots in addressing the needs of military, especially the efforts of the
Early efforts to improve the efficiency of training focused on observable behaviors. The models in use required that tasks be subdivided into subtasks, with each subtask considered a separate learning goal. The benefits of this approach are obvious. If there is no margin for error assumed, then it does not make sense to guess which components of an activity a learner could perform -- in essence, a "chain is only as strong as its weakest link" approach. The goal of training was framed in terms of a requirement of achieving mastery by all learners, which was achieved through repetition and feedback.
Learning theories were influenced by increasing influence of digital computers in the 1960s and 1970s. As a result, many models adopted an "information-processing" approach. More recently, an important trend in Instructional Design is recognition of the importance of managing and optimizing cognitive load during learning activities.
As an Instructional Designer in a corporate setting, it is very valuable to keep abreast of research findings related to learning. This is a vital and evolving science. Keep in mind that the ways that people learn do not change significantly over time. Rather, our understanding is being increasing refined. Many of the bedrock principles of Instructional Design are well established and will remain useful, so it is advisable to keep a balanced perspective on what appears to be “trendy” at any given time.