At the risk of sounding flippant, what Roman idea of consuls? The consulship went through several different forms over several centuries. When you say that the consuls "switch off their control every month" I presume you're referring to the post-Sullan practice of rotating consular presidency over senatorial meetings between junior and senior colleagues. But that's a feature of Roman political structure that became common relatively late. In order for consuls to rotate their presidency over senatorial meetings (which is hardly "control" of anything important, since basically all they can do is determine the order in which people speak) they would both need to be expected to remain in the city for most, preferably all, of the year. But for most of the Republic, from at least the late fourth century to the early part of the first century, the consuls typically spent only three months in the city, arranging domestic affairs (typically in support of their upcoming military campaigns, like making sure there was food and stuff) and--especially--enrolling citizens in the legions. The consuls of the middle Republic were military commanders first and foremost, and really only returned to the city in order to preside over the elections of their successors, which in the second century often was impossible, resulting in elections frequently being presided over by dictators. In their duties as military commanders, which is really what the consuls were, they were highly successful, although by the first century inadequate. That's a statement that doesn't really make a lot of sense, however. If Roman consuls were supposed to be military commanders, then what would their "success" be in that office? Going out to take up military action in their provinces? Officially speaking the consuls until Sulla didn't really have much in the way of additional duties. By the end of the second century the two consular armies were however insufficient to deal with the military affairs of multiple provinces (which were meanwhile increasingly being defined territorially), and even the ad hoc practice of investing proconsulars with imperium or assigning praetorians to provincial command was not really sufficient. Even after Sulla the consuls do not really seem necessarily to be thought of explicitly as a regulatory force, if they were even though of "constitutionally" at all. Cicero interjected his own opinion as consul into the debate about the Catilinarians, but this was highly unusual and he faced a lot of fire for it--post-Sullan consuls merely made sure that everybody spoke in the correct order. Likewise, Cicero called a contio as consul against the Rullan bill, but both the practice of calling an anti-contio against an opponent's bill and the practice of a consular calling a legislative contio at all were both highly unusual. Would it be more accurate then to say that Cicero understood the consulship as a regulatory office? Maybe: it's an argument that would have to be supported. But really what other regulatory powers did the consuls have? The SCU? That only appeared in 121 and was assigned by the senate, with no consular agency before the fact at all.