Perhaps you’ve forgotten to add a child theme, inherited a site without one or thought you might not need one until now. Maybe you want to save complex customiser setting for another project. Either way there is a great plugin from the WordPress repository called Customizer Export/Import that could save you time.
When you install and activate the Customize Export/Import plugin go to the customizer and you will find a new Export/Import panel. As the plugin was made by the Beaver Builder Team those using the Beaver Builder theme will be able to install and activate it directly from the customizer.
It doesn’t export settings that aren’t stored in the database as theme mods such as Widgets, Site Title and Tagline. It does (since version 0.7) export custom CSS in the customizer.
When’s a Child Theme needed?
Child themes allow you to modify themes and sometimes plugins without having this overwritten on updates. It is arguable when you should use it .
For example the custom CSS can be added to the main theme’s customiser without being overwritten. The excellent Code Snippets plugin could be use instead of adding the child theme’s functions.php file
I personally a child theme by default because 90% of the time I will be changing CSS in the (child) theme’s styles.css file. I do this as I generally prefer it a separate file for CSS over it being printed to the source code of every page (Not all CSS will be relevant to the page I’m viewing and I like more editing space).
Also a good many times I will need a child theme to modify something in a plugin (for example: an order email template in WooCommerce).
There is not clear right or wrong and you could use the Customizer Export/Import to move from Child theme to Parent is not needed and potentially (although perhaps imperceivably) improve performance.