When you build a model, to ensure efficiency, it's important that you consider the model's size. For example, you can use line item subsets and numbered lists to control the size of your model.

Line item subsets contain line items from the same or different modules in a model. If you want to manage the size of your model, use line item subsets to avoid line item duplication in other modules. To avoid further duplication, you can also use the COLLECT function to pull values into a target module from a source module. 

Additionally, it's best practice to set your line item's summary method to None, and only use another summary method when you need it. This approach ensures that aggregated cells are only calculated when you require them.

You can also incorporate numbered lists to increase model efficiency. Use numbered lists to manage duplicate names in a model, avoiding empty cells.

It's also important to consider the number of dimensions in your model. For example, if a module contains more than five dimensions, you should split the module in two. 

You can view the size of your module in the Cell Count column in Modules .