I used to spend hours arranging my barbies, and stuffed toys in rows. I would take my line down again, and make a new rule for the order, and begin a new line. The order might be by animal type, alphabetical, color, or even by most favorite to least. I LOVED playing 'store' and would spend hours arranging all the 'merchandise' in my store. I even made little price tags, and and sales receipts. I spent 10 times longer setting up my store, than actually playing with it. I mostly liked playing with my brother, because he had to play my way. I didn't have so much control over other children. I wasn't very nice to my brother, and would often smack (I'm embarrassed to admit that!) him when he didn't obey my rules.
Now, I do this with adult things.
I hear lots of people say they don't know about things in their closets, and such. I know every last place in the closets in my home. My boys' closet, for example, I have everything measured up by size, because it is the most logical to me to use things that they will grow out of first. So, I will measure every item of clothing up to the others, and put the smallest ones first. I cannot stand when this order gets messed up. Clothes in my closet are by category. I sort my husband's by work clothes, and good clothes, because he doesn't do well in discerning for himself in this area. I could find anything I wanted to in my closet blindfolded.
My pantry is the same way. Everything has it's place in little lines, and it never changes.
Everything in my house has a rule, and an order. It's my way of making sense of the chaos. I need this to feel safe. I need this to feel predictable. Some would see this way of living as stifling, but I see it as a way to calm my inner nerves. I like rules, They make sense to me. If I can apply a rule to something then I can make sense of it. Dinner is at 6, and the floor gets vacuumed every other day. These are rules in an otherwise chaotic world that help me to function. Bubby seems to be much the same. As long as he has a rule, then he can follow it. When he was little, I would give him 'the rule' when it was time to do anything. Like, if we were cleaning up, I would say pick up the red legos, or blue trucks, and he would get right to it. He now had a rule to apply to the big messy, broad idea of "clean up". Our brains work in specifics. Timers work well, too. Brush teeth for 2 minutes, clean for 5. It worked. It took what appeared to everyone else to be a defiant child to one that was eager to do what he was told.
My childhood fixations on lines of toys have turned into an adult fixation on lines of household items. The behavior never went away. I just learned to use it differently. Many parents don't like it when their child spends long periods of time arranging their toys, instead of using them functionally, as they were intended to be used. What they don't understand is that these behaviors serve a very important function for us, and can be used in very productive ways as adults.