I have several HC620's in use at various properties with HA and the batteries all last 4 - 6 months for me if I'm not using rechargable.
How exactly are you using them with your HA setup? Are you directly programming / managing them yourself with automations or using something like KeyMaster Z-Wave lock manager and scheduler or Custom Component: Lock Code Manager - an integration to manage lock usercodes across multiple integrations (Z-Wave, Matter, Zigbee2mqtt via mqtt, Schlage WiFi)?