It's been pointed out that chapter 4, posted earlier this weekend, is rather short. Coming in at only 2500 words, it is the shortest chapter in the book and about half the size of most chapters.
I must admit that I don't watch chapter size as I write, rather it is the story that drives chapter length. Looking at the chapters to come, it seems that there is a definite trend for chapter size to increase as the book progresses - one chapter is nearly 7000 words.
I think that 'even chapter sizes' may have become the norm as a result of stories being published as serials in magazines. For example, The Sherlock Holmes stories were published as a serial in the Strand (monthly) magazine.
Be that as it may, TMEA chapters vary somewhat in length.