Is it a rule or just a habit?

I believe it is the habit of your teacher.

I know that adjectives should be arranged in a particular order depending on the type of the adjectives. You can find more information here:
http://en.wikipedia.org/wiki/Adjective#Adjective_order
or any English Usage book.

But I've never heard of this "put the adjectives in Alphabetical order" thing in my life. Well, it may be due to my ignorance, so I searched the web. But I didn't find it too. I just found someone said in a web page:
"Alphabetical order is meaningless for ordering adjectives in sentences."

On the other hand, I found a lot of examples in English grammar books and dictionaries showing non-alphabetical order of adjectives of same type.

e.g.
a tall and elegant lady
a yellow and black sports car

2007-04-07 00:38:47 補充：
For adjectives before a noun, there are rules to arrange the adjectives of different types in particular order.e.g. a yellow and black sports carFor adjectives used as the complement of a link verb, there are no such rules.

2007-04-07 00:43:39 補充：
In any case, arranging adjectives in alphabetical order is not a rule.e.g.He is smart and efficient.PS: The example in the above 補充 should bea silly old man (not a yellow and black sports car)

I have asked my teacher from England.She says this just a habit.If you want to follow the rules,you should put the most important thing at the first.For example: Dani is the top model of America( is the most important thing so put it at the first ),beautiful( quite important )and has a long thumb( not very important ).
If you have any questions,you can ask me or you teachers of teaching English.I think they are willing to help you.