I agree that the way the program operates currently, it is possible to get close to being able to control each station to water for a distinct time. However, in my opinion, this is a difficult way to achieve this for some users. In our back yard, we have 9 zones, some in shade and some in full sun. To prevent over- or under-watering different zones, it is necessary to adjust each station timing to have each watered properly. For example, some zones need 15 minutes and some only 3 in the summer. This changes over the year as the weather gets colder. In addition, when it is dry here, I often have a second program run to water some zones in the afternoons. Of the nine zones, I need at least three run times per program (and preferably more). So, that would be three separate programs, and then additional ones for the afternoon programs. For some of the larger installations, this could get even more complex.
I think the OSPi is perfectly functional as it is, but adding greater flexibility to the scheduler would be great. As for the exact time a station is activated, I agree that this is less important.
BTW, I don’t see an option for controlling sequential mode in the OSPi. Is that feature only available in the Arduino based OpenSprinkler?