I have two 13 month olds, a 20 month, a 2year old, a 3 year old and my own 2.5 year old. I find that 30-45 minutes is all I can get out of the youngest ones because they can't do much and then they get cold because they aren't moving aruond enough (or they don't have the right clothing...see my vent post...LOL). Sometimes if it is not too slippery we go for a little walk and the older ones walk...but even then the babies are just sitting, so they get cold.