I've just learned from Wikipedia that Go Set a Watchman was actually more of a first draft of To Kill a Mockingbird, which explains a lot. Many of the situations in Mockingbird were different in the retelling in Watchman. I believe that as Harper Lee rewrote her draft, turning it into To Kill a Mockingbird, she must have decided to make a number of changes, some small and others quite significant. Then when Watchman was published last year, no one went back to make it consistent with Mockingbird.
I read the book for the following category of the Back to the Classics 2016 Reading Challenge:
2. A 20th Century Classic - any book published between 1900 and 1966. Just like last year, all books MUST have been published at least 50 years ago to qualify. The only exception is books written at least 50 years ago, but published later.I rate it 2 out of 5.