In sailboat racing we often have two or three separate races in a day, and in my watch app I am aiming to capture the start and end of each race with a Lap record (to which I am adding some developer fields). Now that I am processing FIT files, I am trying to get to grips with the Activity recording module and am puzzled about the effect of session.save().
The docs explain save() as :"Complete the session by storing the FIT file on the file system.", but what does that actually do, when would I need to issue it, and why?