Though officially a citizen militia the Roman Army was close to professional. Service time averaged six years all during the Republic, six years away from farms essentially ruined many farmers. This is a well-known part of the reason for the fall of the Res Publica Romana that I have outlined elsewhere and though it was most obvious in the late republic it was a continuing and developing trend through all the Republic's history. Consider the case of Cincinnatus who hurried to win the war and get back to his farm, ostensibly because otherwise his family would starve. Roman citizens could be away for war for six years at a time because Rome developed into a slave economy from the many POWs, but this also spelled the doom of the middle class Roman peasantry that made up 95% of the army. This is all well known, if not, read Brunt. But six years in arms and loss of farms = professional soldiers.
Check Brunt, "Social Conflict in The Republic of Rome" is the short version, or the long "Italian Manpower" both 1971 (800+ pages).
Bookmarks