Every Route has to have 3 out of the 4 paths.
If you wanted to avoid all breast expansion paths, you would only be able to view 6 out of the 24 routes. Originally the game was going to have all routes interact with all themes but I decided against it to sort of give a climax instead of shoe-in the last transformation/expansion type.
I figure with how loose the themes are for most of these things, if you enjoy expansion or weight gain in any capacity you’ll enjoy every route of the game, barring maybe some of the more extreme Lazy routes which can dive deeper into Neet and minor slob territories.
There’s no doubling up on routes either, there’s no pure WG route, or pure BE route, so it’s basically all going to be a sequence of the four types, then pick from the remaining three, and then the final two with the last week playing out as a sort of “This is the result of everything,” ending.
I invented a system when writing the game to easily keep track of what routes were being written. WAL would mean “Weight Gain Week 1, Ass Expansion Week 2, Lazy Transformation Week 3” while LAW would mean “Lazy Transformation Week 1, Ass Expansion Week 2, Lazy Transformation Week 3.” Different sequence means different events and locations even if the week two is still ass expansion, it’s going to be WA vs LA, Ass Expansion with a weight gain focus vs Ass expansion with a Lazy Focus.
Ultimately if you just want weight gain content you’ll feel very happy exploring the 6 routes starting with W, but you’ll also be happily surprised to play any routes that have a week 2 W as well. This goes for any of the other transformations or expansions. The game is about all four and tries to focus on what it means to be a balance between at least three of those by the end.
TL;DR Every Route will have 3 out of the 4 transformation/expansion types, you can have routes that avoid Breast Expansion or Ass Expansion completely, but they have to have at least one of those, using your example.
EDIT I just realized you meant in the flow chart it had all 4 things in one route, good eye!!! Yeah that’s old! Sorry about that!