Question regarding training in the Pre-Marian army

[Bryan]

Thank you for the detailed Answer Bryan!
So fighting in manipular legion could be learned pretty quick same as fighting in hoplite phalanx?

Yes. A hoplite phalanx requires little actual skill at arms or mastery of drill. For everything the Spartans were able to do with a citizenry dedicated to nothing besides warfare other city states could replicate nearly as well by doing it only part time. What the phalanx required was bravery and discipline, to maintain ranks even during the chaos of close combat. 

The Roman system started as a hoplite phalanx and then merged into the manipular legion when they abandoned the aspis/clipeius as an infantryman's shield, when they started breaking legions down into maniples (instead of centuries), and when they started adding intervals into their line, all of which better suited fighting not in open and relatively flat plains, but in the more mountainous regions that Samnites thrived in. There is a reason that in Greece you can find a battle site that had been used a couple dozen times for major pitched battles, because hoplites would seek out those flat spots to fight their battles. Romans tried to do the same early on but either against the Gauls at Alia (where the flank of their phalanx was turned), or against the mountain tribes of the Samnites, they realized that they could no longer fight as a phalanx, a solid continous single line. Whereas the Manipular legion has numerous lines (as reserve) and has articulated and independent maniples (handful of troops) which can react better to different terrain. In addition the scutum allows better protection and does not require a shield mate to the right to protect your own right side, an individual can protect himself and not rely on anyone else. Even before swords became the common Roman hand to hand weapon, a warrior armed with a spear and scutum has more independence in a fighting line than somebody with a spear and aspis. 

Roman in a maniple would need to know a very few basic commands but nothing complex. Some basic facing movements, basic counter marches, testudo, opening and closing ranks and files. They didn't need to march in lock step formation, there was no need at all. There was no need for precise facing movements while marching. There was no need for file leaders. 

They would have benefited from conducting practice charges/advances, throwing the pila in unison (which dramatically increases the psychological effect of a barrage), going from Testudo to the attack in open order (something commonly used against skirmishing enemies). It would have been good to have maniples fight each other in mock battles with staves and sticks, that would help condition them mentally to the psychological effects of close combat and partially innoculate them to the stress. 

But like many Greeks believed there was no need to teach spear or sword fighting, because it was instinctive, instead focusing on discipline and bravery, the Romans believed the same. Virtus, roughly translated to manly courage, was tempered by iron fist discipline that made the draconian discipline imposed by the Wehrmacht and Red Army seem like child's play.