CATM is a seperate branch inside SF. You generally switch over and stay there. For years. Sometimes if manning's tight they'll pull you (I deployed with a CATM SSgt who had that happen, he was a regular line NCO instead of CATM as we didn't have a role for that) but they generally stay in CATM from SSgt through TSgt since there's not too many MSgt spots in CATM available, then go back to flight or retire.
"And Shepherds we shall be. For thee, my Lord for thee. Power hath descended forth from thy hand, that our feet may swiftly carry out thy command. So we shall flow a river forth to thee and teeming with souls shall it ever be. In nomine Patris, et fili, et Spiritus Sancti. Amen."