Joomla native routing is not quite robust and you can't control how the SEF URL of menu item is built. You can only define menu item alias - a component of URL.
By default aliases of Joomla menu items are relative: aliases of all parent menu items are auto-prepended to SEF URL.
So child menu items have URLs like:
This plugin allows you to switch alias to 'direct' mode and have short URL without aliases of parent menu items:
It would be much more userfriendly, if one could mark many menu items at once and make them "direct-aliased". It is pretty bunch of work, if one has many menu items - open, press button, save, open... It would be so fine and quick: in the menu items list: mark all up, press button "make checked direct-aliased" and you're done:)
This plugin is the answer. Its free, it took less than 5 mins to install and activate and it means I can have simple URLs like www..com/landingpage
It should also be cross posted in the Landing pages catgory of the JED.