My 11 month old daughter started walking about 2 months ago, and is now a very strong walker for her age. I've taken to letting her walk part of the way whenever we're going somewhere (pushing the stroller with one hand, and holding her hand with the other). Whenever she gets tired (she never lasts more than 500-600 meters) I put her in the stroller and let her ride the rest of the way. I am now starting to wonder when I'll be able to completely leave the stroller behind and let my daughter just walk everywhere with me, which leads me to my question.
At what age is the average child ready for longer (about 5 km, possibly broken up into two parts with a small rest in between) walks?