The Japanese use of Arquebus was not the same as the Europeans and the general perception didn't always fit. Oda Nobunaga was famous for using "multi-stage shooting" for the longest time people assumed that this was the rank fire method used in the west, and then thus assume the same application of firearm in the west fited into the Japanese mode.
Except that assumption is wrong.
What the Japanese did was something altoghether different, they seperated shooters from reloaders. aka a team of (usually 2 ) men make up a shooting uint, the shooter would be in charge of aiming the shots and fire the gun, while the reloader carry at least one (and often 2) spare gun to reload while the shoot shoots. The Arquebus was also not the same thing as the later musket, it was usually smaller and lighter (espiecally the Japanese Teppo) and thus with enough quality craftsmenship you can achieve a decent degree of accuracy with the gun in the hands of skilled shooters, this is testified by the fact that there were numerous recorded examples in Japan at that time of attempts to assasinate prominent figures (such as Nobunaga, and Hideyoshi etc..) using Arquebus, a strong evidence in that Japanese did not use the Teppo as a pure point and fire weapon.
Thus the shooter was considered a true skill position , and were very often drawn from lower samurais, who would have the training to aim guns properly (the general feel of hitting a moving target etc.), while the peasant Ashigarus more often served as the reloaders, where skills can be acquired with repeated training in a realtively short period.
for example, Akechi Mitsuhide, The man that betrayed and killed Oda Nobunaga, was a well known marksmen with Teppo, while serving as a minor retainer in his earlier days he was recorded as to have shot down a flying bird from around 50 meters away.