All of the edges and faces should be created and left on Layer 0. Groups and components can have other layers assigned to them. Or they can be assigned to other layers, whichever way you want to look at it.
Layers are used to control the visibility of groups and components. Layers do not provide any separation between various bits of geometry. That can only be done by groups, component and actual space between.
You may have associated the groups with Layer 0 but unless you associated the geometry within them to Layer 0, you haven’t fixed the model.
Creating either groups or components is like putting the selection inside a container that protects it from being modified and to make changes, such as trimming the ends of your OSB panels, you need to open the container to change it.
Components have some properties that groups haven’t. Editing one instance of a component in the model results in other instances (copies) getting the same treatment. Editing a group means that group gets modified but none of the others do.
It really is pretty simple but you need to start with the right approach. If you want, I could demonstrate after I finish dinner.