The layout attached to the sheet rule comes into play below the top level of a tab or link to screen button. If you have multiple tabs that all refer to the same sheet, you can design each tab independently because it is the top level. If each tab contains a list and you then view the details of each list item by clicking on it, then the details will have a layout that is shared throughout the app because you are now at the second level below the top level of a tab. Layouts are still attached to sheets, but only the details layout and only once you drill down into those details from a top level list.
In my app, I have a list of student lessons that are listed and added from the top level Lessons tab. The details screen of each student lesson was designed at this point to my liking. Drilling deeper into the app, I have billing and invoicing and I can have a relation that can pull and display those student lessons for that billing period. When I add a relation to the relevant student lessons in the lessons sheet, I can add an inline list withing that billing section and when I view the details of each lesson in that list, the layout is already set from what I did previously in the Lessons tab.
As I always say “layouts are tied to sheets”, but this only applies at any level below a top level tab or link to screen button. Basically viewing the details of a list item will respect the layout throughout the app.