I didn't realize that they pre-planned the length of each series. I guess I always thought they simply based it on sales. Although some of them would be obvious in length. I have been lucky - my Madame Alexander is on it's 21st year, the Puppy Love series is on its 26th and the Fairy Messenger is on its 12th. For my younger daughter, I started several short lived series before we settled on the Fairy Messengers. I am always impressed by the Frosty Friends series which is on its 37th year. I was given the 1st and 7th in that series as gifts and wish I had kept up with them. The first one is worth over $500 now.