Wow you guys just love to argue semantics this is now getting so far off topic its silly we are now on mediaval weapons & yes main benefit was a weeks training & you were pretty proficient but like any weapon it developed & was very good at piercing armour. In the Romans case it was the for runner of the MG to using tactics similar to later musket men. Fire off your "magazine" & reload. Nasty weapon for the day.
On semantics I would not say the tanks role is to take & hold ground its more to support the guys that do this good old Mr flexible infantry without them its nothing more than a mobile gun platform waiting to die.