How do I use my Kokuyo Campus daily study planner

I’m new to using planners and wanted to make my studying more organized and help with developing good study habits. I’m confused as to why the hours on the time table section starts at 4 and ends at 3, I understand it’s using 24 hour format which I prefer, but I don’t get the reasoning for how it’s presented.

I can use it as is just fine but I would like to understand why it’s formatted the way it is so I can use it effectively and efficiently.