A soldier's training takes at least several months. Certain basic things require time for Yuri to remember and develop reflexes. Physical training also needs time. However, for machine gunners, if only teaching the basics, even a day is enough.
The operation of a machine gun itself isn't that difficult; you can learn it quickly.
But to train Yuri into another Big Dog, another Machine Gun Artist, that's tough. Many things can only be learned and understood in combat. Glolov's guidance can only shorten this process, but it can't fully replace Yuri's experience in battle.
Even without the expectation for Yuri to become the next Big Dog, just training him to be a qualified machine gunner would take some time. Good shooters are raised on bullets; this is true for snipers and still true for machine gunners. When Yuri's shoulder and hands are callused from shooting practice, he'll naturally become a good shooter.
