Often us readers enter a trance and the book which we’re reading is the only thing on our mind. I used to be like this with most books when I was in middle school but now due to academic pressure I do not invest my entire time to a book. Lastly, the Divergent trilogy took me the shortest time to complete- I finished the entire series in three days.
The Kaiju Preservation Society and Starter Villain, both by John Scalzi. Short, uncomplicated, and lots of fun. About 4 hours each for me.