If the same assets are used by two consecutive layouts, they don't get unloaded and reloaded.
If you don't want to use layouts to manage memory, don't use different layouts.
For organizational purposes on a single layout, you can use event sheet includes and restart layout action with a variable to determine which sub game to load.
On the other hand, if you don't understand how it works, you probably don't need to worry about it. It doesn't make sense to have assets that are not in use kept in memory. Also if you don't understand how it works, you definitely don't want to manage memory use yourself.