Looking through the code, it appears that Zimmerman can be between 0 and 200%. The manual doesn’t document the extents.
For me, a configuration limit for the computed % Watering factor would be great, so that I could configure it. I could set it at a max of 100% with 15 minutes of watering or a max of 150% with 10 minutes of watering, and comply with the local water restrictions. I am happy to do the coding if that helps.