How did Charles Lindbergh use dead reckoning over the Atlantic ocean?
It's actually "ded" reckoning (short for deduced), and it doesn't involve landmarks, it is simply flying a heading for a certain amount of time, that's it.  When you start adding in landmarks and things, that is called "pilotage."

Typically, visual navigation over land is mostly pilotage, with a bit of ded reckoning occasionally.  When you get over the water, like Charles Lindbergh, you do mostly ded reckoning.  When you do have a chance to use a landmark, you can update your location and basically restart your ded reckoning from a known point.  Lindbergh also used the stars to update his position and based new ded reckoning tracks on those positions.