The information is interesting but superficial. There are too few demo videos for a paid app, and the videos don’t even really demonstrate the skill.
Further, the app has very few interactive/dynamic features. Most annoyingly, the dates for the leaps. You can’t adjust these according to when the leap is actually happening, or track signals on a day to day basis per leap.
The weeks start on a Monday no matter your due date which makes no sense.
Better to read the book & just mark your own calendar ….