How many zones do you have? Assuming your flowers and shrubs are on different zones than grass your data will be different for each zone based on plants in any particular zone so it will water each zone differently. Example shrubs it may water for longer and less often but grass more often and less time. Just an example, it all depends on what you have and if you enter it into the zones. I have all my flower beds and shrubs on drip lines, so they water 2 hours for each zone and on totally different schedules when they do vs my grass.
Also, mine for example also waters the grass I have that’s mostly shaded differently than the grass that is in full sun all the time. It’s on the same schedule, but the zones will be watered on different days sometimes and shaded ones for longer times, and slightly less often. You’d never know it by looking at the grass, as it all looks the same and nice and healthy.
Even with flex daily you can still adjust what days it can not water, so you’d not have wet grass on mow days, etc. personally I have mine so they don’t water the grass on certain days but the shrubs can water any day. For any zones that have different day requirements you would simply create a different schedule. Example, I have one schedule for my shrubs, one for my grass. Another off shoot of that is when it waters. You can set end before sunrise, or start after sunset, or enter a specific time for any of these. I set my schedule with my grass to finish before sunrise, shrubs to start after sunset. It takes care of making sure they don’t ever try to water at the same time.
Historic data isn’t really a driving factor, other than a starting point for zone length each time it waters, for the month. Mine changes a few minutes from month to month usually, with longer times for summer and shorter in winter. With that said you can manually adjust that as well.
It really uses local weather data to determine how often it will actually water and such. You can also set the limits on that to, so for example anything less than .25 inches of water and it ignores the rain event that day. Anything over and it will know to add that rain into its calculation. And you can adjust that tolerance as well. Also it gets how much rain was measured and uses that in its calculations, it doesn’t assume the same amount of water every time. You can get your own weather station and connect it to the rachio at your house so it knows exactly how much it rained at your actual house if you want. It would basically do as you suggest, if it got half the water it needs each time it waters it wait an extra couple days or whatever it would be before it watered again, longer if it rained a lot, less if it rained enough to measure but not enough for much more than a day.
And there is a nice graph that will show you what is currentLy calculated for the soil moisture, when it’s currently expected to be depleted enough that it will need to water again. As you adjust data points that graph would change. And if the weather changes the graph may as well. One nice thing it should do as I recall is if extreme heat is coming it might water a day early because it knows the water will deplete faster. This is especially helpful if you don’t allow it to water on many days. Example. It is schedule to water Tuesday then on Saturday and never on Friday. It sees weather report saying massive heat wave coming Thursday. So it’ll water Thursday because it will know if it waits till Saturday the soil moisture will be depleted further than acceptable.
Anywho if you did try one, you’d need to have the will power to adjust data and settings and not mess with water times directly for the most part, then slowly dial it in to get it working as you’d expect.You’d want to give it time to get going to. At First it may water extra because it assumes the soil moisture is somewhere near 0. But after a little time it settles in and is pretty smooth running.
If you really want to try it, I’d suggest getting one from Costco. Can always return it after three or four months if you don’t see the benefits. But you’d need to trust its choices once you gave it all the data and got it tweaked. You may not notice how nice it would be till you are well into the next season, and realize you didn’t have to adjust it’s data points or settings to get it to water differently during a different season, But I’m sure enjoying that, especially also when we have a big heat wave.
Anyway, just making sure you get a full picture of how it works.