Smart models can be used for many purposes. When to use them? As a general rule, when there is repetition in the model, you want to model only once, but you do not want a closed subassembly (subproject). For example, you can use a smart model in the layout phase or in a floor panel in the bathroom to embed a floor module.
In connection with the frame parts, the part cutout zone is also useful together with the smart model: