I’ve read your other thread too. Just FYI:
A “Nest-type” system would require you to manually water, deciding for yourself, how long and how often to water. It would then learn your settings and continue them for you. If you got them all right, it would work well, but it’s hard to get right.
A “Simple” system would require you to manually water, deciding for yourself, how long and how often to water. It would then stay that way, until you modified it to better determine if you need more or less water.
A “Smart” system can do two things: Do all the calculations to determine how much and how often to water - but it needs to know facts about your specific conditions to do so. It can also water more or less often, depending weather conditions and rainfall. This is what Rachio does. It can’t do that without knowing what you have, specifically, and the weather around you.
So, for each of your three zones you have to go through the selections and set what you have: soil type, sun, crop type (your trees, grass and garden), of course where you live (determines weather) and type of sprinklers you have. Most of that can be dialed in pretty well, and you should be able to make those settings. For a well-installed system, those defaults are pretty good. And smart. That’s for the zones.
During setting your schedule, you have three choices: Flex Daily (uses local rainfall and temperature conditions to determine when to water), Flex Monthly (uses average monthly temperature conditions to determine when to water), and Manual/Fixed (which uses YOUR estimates of when and how to water, but tries to help you along some, and can vary the values by month). The smartest, and I feel best, schedule is Flex Daily. Once dialed in, it can run with little or no attention, which is no doubt what you want.
I mentioned dialed in, and for a well-designed system. One of the questions for each zone is the sprinkler head type, fairly easy to determine. But - a system can be designed to put out a LOT of water evenly, or a LITTLE water evenly, even given the same head type. So techy people (like me) take an additional step by using the Advanced settings to calculate how much water is placed in the zone per hour. Either using catch cups, or calculating area and water flow. Yes, that’s not “smart”. But with the large variation in irrigation system designs, you can either use the standard values, and then increase or decrease to get a better average amount of water, or calculate it with one of those methods. That’s one of the main complaints people have, trying to determine the actual flow. But it is just as necessary with any system, unless you just dial it in by trial and error. Installers may tell you 20 minutes per zone. But each installation will vary the actual water put down in those 20 minutes.
Nevertheless, you can and should start out with the defaults, maybe compare total run time per week with what you’ve done in the past to add a little a “your smarts” to the system. And get into advanced only if you need to. Oh, and of course there are people here to help you with that.
Hope this helps.