Magic age is 6?

I read an article that said 3 kids is the most stressful amount of kids.  Even four or more kids aren't as stressful.  I thought this was interesting and read the comments on the article.  A lot of them agreed 3 was stressful.  Some with more kids tried to state that after 3 they just relaxed more and stopped needing everything to be perfect.

Now I believe this to a point.  But I see something else.

If you have 3 kids, and the average age between them is two years, then you have kids that are 4, 2, and newborn.  IF you wanted a 4th you would consider it when they were 5, 3, and 1.  From the study and comments most people don't consider it.

Now assume you had that 4th child.  You have a 6, 4, 2, and newborn, but something seems easier?  It didn't make sense to me until I realized this has to do with the age of children. 

6 years old.  What does that mean to most Americans?  School aged kids.  If your kids are 2 or more  years apart then your 4th would be born when your 1st is in school, 5th when the 2nd starts school, and 6th...wait, who has 6 kids these days??

So the reality is that once you have more than 3 kids it will feel like you only have 3 because the oldest will be in school.  Well, at least for 8 hours during the day.

There are a few other things to consider.  At 6 you start extracurriculars (you can start earlier but most kids are in something by this point), so right after school you're off to ballet or basketball.  Once you have a 6-year-old they listen better, so you're not as stressed out with that child as with the 2-year-old coloring on the walls.  Also, what if you do have more and more kids.  7 kids at two years apart are 12, 10, 8, 6, 4, 2, and newborn.  Unless the 4 oldest are all boys you will probably have one girl who would love to hold the newborn all day.  The 8, 6, and 4-year-old can probably keep each other entertained.  While you do have to worry about all of them, they entertain each other a lot more. 

So from all of my thinking and rationalizing it seems like the magic age is 6.  If you can survive until your oldest is 6 then adding another one will be hard, but a lot easier than adding #3 was.  I'll admit a lot of this is my personal thinking, but there is some logic to it.  If I ever get to the point where I want to add #4 I need to re-read this just for the logic of it and see if it is total BS or not!