This Behaviour helps to view time/date/timestamp/datetime from db to local Date / Time / Date Time format and in local Timezone. And save into db in with db timezone and db format. You only need to include this behaviour in models where need this facility.
Countries sometimes change their laws pertaining to time zones and daylight saving times. This means that GMT+2 can be a different local time this August compared to last August! It could even be a different date!