I second this idea. The baseline values and factors probably work well only for certain climates, and won’t be correct for most users. It’d be great to have the script integrated into the local OsPI firmware (I actually was surprised not to find it there). I mean, even an early Raspberry Pi has the power to run a short python script before calculating the water cycle. For me, that would be enough as I then could alter the values in the python script itself. I wouldn’t mind doing that in imperial units.
Edit: I think landscaping experts agree that you shouldn’t water your garden a bit every day as the water then has no chance to reach the roots. It’s better to water only once or twice a week, but then thoroughly. In summer I usually water twice a week for one hour per zone. If this scheme is used, then the weather algorithm has to consider the weather of the past week and average it out to produce usable results.