How many years can a sergeant's staff be competent?

According to the information I know, the maximum service life of a sergeant's staff is 55 years old. The specific length of service may vary due to length of military service, rank, position and other factors. In addition, in some cases, the staff officers of non-commissioned officers can retire early or transfer to civilian posts. If you want to know more about the length of service of non-commissioned officers, it is recommended to consult relevant laws and regulations or consult professionals.