1 Chronicles 27:1-15
This is the list of the Israelites—heads of families, commanders of thousands and commanders of hundreds, and their officers, who served the king in all that concerned the army divisions that were on duty month by month throughout the year. Each division consisted of 24,000 men.
In charge of the first division, for the first month, was Jashobeam son of Zabdiel
the division for the second month was Dodai the Ahohite.
The third army commander, for the third month, was Benaiah son of Jehoiada the priest.
The fourth, for the fourth month, was Asahel the brother of Joab
The fifth, for the fifth month, was the commander Shamhuth the Izrahite
The sixth, for the sixth month, was Ira the son of Ikkesh the Tekoite.
The seventh, for the seventh month, was Helez the Pelonite, an Ephraimite
The eighth, for the eighth month, was Sibbekai the Hushathite, a Zerahite.
The ninth, for the ninth month, was Abiezer the Anathothite, a Benjamite.
The tenth, for the tenth month, was Maharai the Netophathite, a Zerahite.
The eleventh, for the eleventh month, was Benaiah the Pirathonite, an Ephraimite.
The twelfth, for the twelfth month, was Heldai the Netophathite, from the family of Othniel. There were 24,000 men in his division.
Why?
Twelve families and there 24000 men to protect the king and their nation. This division in turn to serve their duty, the benefit is not too heavy duty and they may rest and training in the other times.
How?
Good arrangement and equal treatment of every servant is good to the country and good to these armies.