The four phases of instruction give a concrete framework for planning the sequence and types of activities for learning.
However, the cycle of content presentation and learning is often messy. Many concepts, theories and skills within a course are related and are not easily separated or learned in isolation. This means that often, some things are learned side by side. Therefore, the flow of instruction can vary depending on the content.
Resources & Further Reading
Reducing Cognitive Load:keep it simple (Stanford University Teaching Commons)