This can cause an integrity issue if you Home Assistant is shut down during your delay. Then on the next start, your automation will be permanently off.
Better to use a condition like this:
condition:
- condition: template # only notify once every hour at most
value_template: "{{ ( as_timestamp(now()) - as_timestamp(state_attr('automation.notify_me', 'last_triggered')) |int(0) ) > 3600 }}"