Actually that is not too far from reality. Data that will be allocated only once does not need be freed. You really only need to free memory that may increase iteratively. If the memory is not used frequently it will end up on swap without major implications. If it is used during the whole execution, it will only be freed when the program ends; there's difference if it's by a 'free' or by the OS; there's just no difference.

As an example, constant data that is allocated by GNU Nano is never freed. AFAIK, the same happens when you use GTK or QT; there were even tips on how to suppress valgrind warnings when using such libs.