This late note from Debbie Gibbons at National Geographic Partners:
I can't speak for atlases that do new editions each year, I believe Oxford is one.
We do reprints each year or as needed and mostly just fix any errors that have been found.Every 5 years or so we do new editions and those are completely reinvented—new design, new content (new thematic and reference spreads), all spreads updated with new geography and data as needed, updated boundaries, capitals, etc. At a minimum we create 7 new reference spreads although with the last one we did 17 brand new spreads and we had 5 brand new thematic spreads with all others receiving major overhauls.