@fpuig, welcome! Thank you for joining the Rachio community
The Rachio controller will recommend watering durations for each of your zones using the information provided about each zone. For more information on how it does this, please see this support article & video.
Flex Monthly schedules will auto adjust your watering durations and intervals on a monthly basis. Here's a good FAQ on Flex Monthly schedules -- let me know if it helps explain how the schedule works. Expect to see a Seasonal Shift email the first week of each month with an update of the changes made to each zone.
Hope this helps!