The manual you are reading is for the Arduino version (not raspberry Pi) which runs a different firmware than the Raspberry Pi.
There are many forum posts discussing the differences between the Arduino and Pi versions but one of them is the software. The Arduino runs a firmware written by Ray in C++ whereas the Pi software is written by Dan in Python.
The software moves at different paces and are not necessarily inline with each other. With that said, Dan has commented per-station watering is in the works.
My application detects your device and firmware and shows the appropriate settings as needed. Since your using an OSPi, the global watering time is used rather than per-station.
Thanks