Software threats are not static. As a result, the process used to secure software cannot be static. Organizations should take the knowledge learned from practices such as root cause analysis, policy changes, and improvements in technology and automation, and apply them to the SDL on a predictable schedule. Generally speaking, a yearly update schedule should suffice. The exception to this rule is when new, previously unknown vulnerability types are identified. This phenomenon requires immediate, out-of-cycle revision of the SDL to ensure proper mitigations are in place going forward.