YOU DECIDE WHAT IS IMPORTANT TO YOU
How granular you make it is up to you, because it is YOUR book. For example, it can make sense to create a daily overview only if a lot really happens on a day and must be collected. For the other days, the weekly overview may be sufficient, because there is already enough space to record everything.
In addition to the individual overviews, which are not created in advance for the whole year, but always gradually, there are variable elements that can be optionally incorporated. These include trackers. With these you can record habits or progress in individual areas - e.g. for your diet or fitness, or you can use them to record your learning progress in a specific area.