What's the easiest way to run an automation every hour and a half?

[Troon]

@Mariusthvdb

using the time_pattern is much easier, and doesn’t waste resources, because it the template isn’t met, the action isn’t executed.

In that case:

trigger:
  - platform: time_pattern
    minutes: "/30"
condition: "{{ (now().hour*60+now().minute)%90==0 }}"

I’ve no idea if that is any less resource-intensive than my prior attempt.