The core tenet of the development of effective training content is to understand the foundational competencies associated with the development of expertise for each role within a domain and leverage this knowledge to tie the training content to the appropriate training objectives. For the past decade, the Air Force has leveraged a process that allows for the dissection of expertise into the core building blocks (i.e., knowledge, skills and experiences) required for the development of expertise, known as the Mission Essential Competency process. This process utilizes three workshops as well as broad spectrum data collection to capture empirical data in order to characterize expertise development and support the identification of training gaps. To date, the MEC process has been used across over 40 weapons systems. Decision makers within the training community have often asked about the longevity of the data collected (i.e., how frequent do the refresh intervals have to be to ensure the data is current?). This paper will discuss our analysis of the change over a 10-year period (2005-2015) in the Air Operations Center Intelligence, Surveillance and Reconnaissance Division across each component of the MEC data collection (over-arching MECs, supporting competencies, knowledge, skills and experiences, and training gaps). This paper will provide the type of change (i.e., semantic versus functional) and degree of change to each component to address the question of determining appropriate MEC data refresh requirements.