They traveled mostly by rental car and used two air flights to get from Greece through 18 other countries ending in Lichtenstein. I didn't see whether their flights were commercial or private since that could have made a big difference in their travel time.
While it was probably a fun thing to challenge themselves with and accomplish, I'd rather do my traveling at a more leisurely pace. Even our world cruise seemed too fast at times when there was only one day in an interesting port and too many things left unexplored.
We've racked up a lot of been-theres in the years we've traveled but it's never been for bragging rights. That said though, I also ran across a site called, The Travelers Century Club. It's a club for those who have traveled to 100 or more countries or territories. I'm not sure exactly how they count some of them since there are islands that seem to be counted as a territory but yet belong to a larger country. If I count all the islands in the Caribbean separately (British Virgins and U.S. Virgins) we would certainly go well past a hundred but otherwise I'd say more honestly it's probably ninety-three.
More importantly, we have had a unique opportunity to explore this great earth and hopefully will continue to do so for many years to come. Travel is about adventure and exploration not speed-dialing and fast-food mentality.