I've been to every country in Western Europe except Spain, over a period of 5 months. I have spent 3 months and more than 18,000 kilometers across Africa including 13 different countries. I managed 20,000 kilometers across Australia over a 2 month span. I traveled through Eastern Europe for more than 3 months, including 5 different countries. Spent 2 months through Scandinavia. The continent that I've seen the least of is South America having only 1 month travel experience there. Mostly focused on seeing Peru. I'm working on changing that to include more countries... I traveled through Asia for 6 months, starting in India and ending in Bali with only 2 scheduled flights. The P.R.C. didn't appreciate my entering Tibet first and then China proper, so they forced me to fly to Hong Kong and back before they allowed me to enter. All said and done, I saw 11 different countries over the 6 months there.
I highly encourage my fellow travelers to take their time when entering a country. I mean if your goal is to say, "I saw ___ amount of countries over ___ amount of time" and you only spend a few days in each country, no offense, but it doesn't really count. The point of travel is not only to see the sights but also to taste the food, feel the sand, smell the flowers, and listen to the unique sounds. If you blow in and out of a country, in a few days, while taking a few pictures and experiencing nothing of the culture and the people, why not save the money and just watch the discovery channel or photoshop yourself into someone else's photos from around the world.