If the INTERVAL referred to above is the INTERVAL that defines the number of days before the program runs again, then I heartily second the motion for allowing an interval of 0 (or 1).
I was bummed out when I tried to set an interval program from once every two days to once every day, and found I had to switch to a day-of-week program to accomplish it. There is nothing easier than adjusting the interval to achieve seasonal changes, and having to switch gears to a day-of-week type program to achieve it seems unnecessary and very klunky. I believe in my case I got an error message when I changed the interval from 2 to 1. Zero doesn’t seem like it applies in this sense of Interval. Am I referring to the same parameter?
I was going to write a few weeks ago, but haven’t even had time to even check in and read the posts.
FWIW, OpenSprinkler is doing just fine in its metal box outside at 108+ degrees in the shade. I removed the plastic cover to give it the maximum convection cooling