Linear thinking is a characteristic of western civilization and began with the Greeks around 600BC.
Ancient Hebrew and Aramaic are languages of eastern thought which is quite different in philosophy and organization.
If we really have a desire to understand the Old Testament authors, we need to unlearn what we know about our own logic process and understand theirs.
Eastern logic is not linear logic, it is block logic. The relation of similar events are more important than in what order the events occurred.
Western (Greek) thinking will say: "This morning when I woke up, I had a nice leisurely talk with my wife over breakfast. Then I went to work and had two meetings, one before lunch and the other at a client's office across town where we came up with strategies to improve sales. After answering my emails, I went home and we had dinner and visited with some friends from out of town."
Eastern (Hebrew) will say: "I went to work, went across town, came back to work, and I went home. I talked with my wife, had two meetings with co-workers and a customer and visited with friends from out of town. I had breakfast, lunch and dinner. I met with colleagues, answered my emails and discussed strategies to improve sales."
In the case of the creation account in Gen 1, the author, not wanting the eastern reader to misunderstand, inserted the words "and the morning and the evening were the first (second. etc.) day" to clearly signal a break from block logic and emphasize that consecutive timing was the most important similarity in this case. God inspired the author to include this knowing that western civilization would be able to understand this account just as easily.
The reason some details of day 6 were left out is, again, because the ancient Hebrews considered similar events more closely associated than timeline. The Gen 2 account is all about God utilizing what He has already made to fashion: Adam from the dust, every animal and bird from the ground, Eve from Adam. Gen 1 is concerned with separating and filling. Gen 2 is concerned with giving personal meaning to what has already been put in place. Hence, it is treated separately.