I disagree with this. What you describe requires that you’ve already survived for several years and managed to establish a secure base and survival group, which is unlikely if one is willing to kill zombies en masse like that. Every zombie encounter comes with the risk of getting bitten, and the more encounters you have, the more likely you are to make a mistake and die. The safest way to survive a conflict is always to avoid it. Even if you were able to make a dent in the local population, more are likely to wander in from further away, and the noise of constant shooting will probably attract even more of them, as well as other survivors, who are an even greater danger.