My Rachio replaced and Irritrol system and I wanted to use it in a similar fashion. Assign a Zone to a time slot and day (odd or even). So that means 12 schedules, each with a single zone, watering at a particular time and duration.
Example: Schedule 1 is Run Zone 1 at 1 AM on odd days for 30 minutes.
After setting all this up, I found that the smart feature had a 15 minute pre-soak, then the 30 minute watering, and then another 15 minutes. So what I thought was going to be 30 minutes of watering turned out to be 1 hour. The simple fix was to turn off the smart watering feature. But it would have been nice to be given this feedback when I was creating the schedule. When I entered the 30 minute duration, I could have been given a summary below of what was going to happen. I know, I could have read the manual but I wanted a quick setup to use this in a simple fashion.