Well, there is general agrement amongst military historians that the Legionnaires after Marius' reforms were of much higher quality. Camp followers, etc was by and large done away with and the army had to carry everything for itself for example. That symbolises a tightening of discipline and a toughening of the troops. Yet it was probably more prevalent amongst good generals than bad ones (Varus' army was weighed down by camp followers and bagage train for example, but they were on their way to winter quarters in a pacified province- or so they thought), and Scipio Africanus has AFAICR done much the same. Perhaps the quality should be variable depending on who recruits them; good generals adding a chevron or something like that.
In any case, I cannot endorse the idea of lowering the quality of marian legionairres and the Polybian-Camillan ones are by no means bad troops. In fact they are amongst the best infantry you can get, as it should be.
If you count on the chronological list of Roman conquests I made, it is 42 conquests and 1-2 firm and romanised allies by 107 BC. No need to use something as inexact as an unprecise online map. But the area of recruitment should be smaller at start, for in the Civil Wars Caesar's oppnents raised new legions in Hellas, Bithynia-Pergamon, North Africa and Spain, so it was doable in emergencies.