Call a kid and ask him to answer 15 question in a row or ask him in during the day part by part but without letting him know he has 15 things to do. Chances are that later will get you better result but yes it depends on kid too but take an average and you will be surprised. I do this with my one year old kid, teach him small small things all day and he learns faster than if I make him sit and ask him to do 4 different hings in a row.
Human Mind get bored because of the number because its kind of tension they see. So if you split it and do things the other way you can do it better. However there are exceptions specially Exam Time when you need to meet a target.
TO -> done is an interesting online service which takes advantage of this human behavior and helps anyone to finish of the small small jobs which gets boring when done in a stretch.
This online application asks you store all your tasks and tell how much time you need for each and never shows you the complete list. Now if you do have time to get any of the thing done just enter how much time you have and it will randomly give you one task to finish. Do it forget it and repeat it.