In the past few years, we have covered plenty of plugins that let you create fancy mega menus, duplicate/export your menu items, and make other changes quickly. Bulk Menu Creator for WordPress is also worth a look. It lets you create multiple menu items at once with multiline text. Simply provide menu item URLs line by line, and the rest is easy.
The pro version of this plugin lets you even do more. For instance, you can include/exclude certain terms, limit how many posts are listed, show login/logout links in your menu, and use variables to create custom menu items.