From what I understand, quick sheets is just like a special folder. You can move individual pages in and out of this “folder” whenever you like.
So drawing some notes in a quick sheet doesn’t mean you can never delete those notes. You could write notes in the quick sheet at first, but then later move those pages out into their own notebook or a dedicated folder with an appropriate name. Or just delete the pages that you don’t want.
In either case, the quick sheets button will always be there at the top of the list, to help you easily write notes even before deciding where they should belong. Kinda like the “Desktop” on a PC.