I was wondering if you always need layouts. Like say for example you create a table for something that will never be worked into a front end design. It always creates a basic layout to go with it.

If the records in this specific table only ever show up in a portal, do I need to keep the layout that was automatically created? Do I need for some reason that original layout to add records to the table through scripts?

No, technically you do not need a layout for a child table. However, it's common practice to have at least one layout per table (based on an anchor TO), usually with all the fields and in table mode. I name mine TBL__________table.

You'll find that 90% of the time, you'll need this layout, even if it's for use with a script (for example, add new record in child table and back to parent) and the user never sees this layout.

You may not need a user layout for it, but it's useful to keep a developer layout for each table. Whether it's periodic maintenance (import/exports) or scripted record creation, such layouts are often needed for something.