You can actually find the answer to questions like this in the FAQ! (Link sadly incompatible with the mobile app but not the mobile browser)
Also, for any changes to the scheduled times, each chapter will have the next update time listed in the notes for that chapter on all three sites.
The posting dates were changed before The Study of the Four began posting due to personal issues, Sunday and Wednesday were the winners in a poll decided by the readers.
Let us know if we need to add anything to the FAQ at any time!
Brothers Apart 