Compared to what? The guy with a spear that had 30 minutes of instructions, sure. Compared to a samurai, knight, Landsknecht, charioteer or any other soldierly caste? Not really, especially not if they use horse as well, since horse training can be the real bottleneck. Samurai are actually an interesting case, since they trained as heavy cavalry, heavy infantry and horse archers before the Sengoku Jidai.
This exact argument of "it requires a ton of training and then you are a supersoldier for the time period" has been used time and again for: knightly shock cavalry, English warbows, double-bladed viking swords, bolt-action rifles and many, many more. The only weapon where I've seen it hold moderately true is the sling, which requires stupidly huge amounts of training and then enables you to slightly outmach bows under 150 lbs draw weight.