"You are busy every day."
Im a native chinese speaker and i am wondering the same thing. 每天你都很忙, 你每天都很忙, both fine.
You did not get it wrong! But somewhat a bit "stiff". It is better write it this way "每天你都很忙".
as a native speaker, I think "dou" should be used. It sounds weird without the word "dou"
Unfortunately with 都 the sentence was marked wrong and the answer doesn't use it. In one exercise they stress the importance of using 每 and 都， but when it used, it is not accepted. Frustrating!
same February 27. Im considering to leave chinese on dualingo, the quality sucks and the maintenance is not really existing either.
你每天都很忙 is still not accepted as Diego565726 and others have said. I noticed the reversed question, in which students must translate from Chinese to English, uses 都 in the sentence.
Why does 很 need to be included? The sentence says "busy," not "very busy" - 很 isn't necessary. I come from a Chinese speaking family by the way
"Everyday" is an adjective, not an adverb and so would not be correct here. What you could try however is "Every day you are busy".