I feel like you may be able to try flex out, and maybe see how it behaves? I don’t want to get you in trouble with neighbors (), but if you are looking to water “smart”, it truly is the best option. I’m wondering if you would necessarily see watering much more than three days a week. That being said, there wouldn’t be a guarantee.
Are the majority of your zones fairly similar in configuration? That would further ensure that they run on similar schedules, and potentially wouldn’t water more than those three days a week.