The Code Talker program did not waive the Corps’ physical standards or its baseline training requirements.

Men who had come from the Navajo Nation — where physical labor was often a daily part of life, where the landscape required genuine endurance, and where the traditions of Diné warrior culture emphasized physical capability — generally met these demands without great difficulty, though the specific routines of military training were new to most.

The specialized Code Talker training came after basic Marine qualification.

The men learned the code — the military vocabulary, the substitution alphabet, the specific Navajo words and their military meanings — through repetition, drilling, and testing.

The goal was not competence but automaticity: the ability to encode and decode messages quickly and accurately under the kind of stress that battlefield conditions would produce.

The automaticity requirement was particularly demanding.