I see. Actually it is a rear but a valid use case when such granularity is needed. e.g. for seed germination program (1:30 watering, 10 times a day) Since the EEPROM is not a limitation for RPi this compression could be removed from those verison.
I modified the firmware and it works fine. Even the GUI allows the setting of such durations with typing in the values directly instead of clicking on +/- signs.