Separating Fact from Fiction (or bad breaks in the text)

After a student of the Bible has spent enough time studying or reading the larger story, or strays from whichever translation acts as his/her Textus Receptus, they uncover the reality that there are some really bad breaks in the Bible.  This phrase does not refer to individuals who had something bad happen to them, like Adonijah (I deserve to be king because of my name) who chose Joab over Benaiah as his sergeant-at-arms or even Shimei who lost his life because of two servants.

The phrase refers to places where we stop reading one section of the text because someone has decided to place a break in the text, perhaps even inserting a title or description of what is to follow.  This happens in Romans 8 that is an explanation of Paul's Thanks statement at the end of 7 or in Romans 7.1 that is a continuation of Paul's second point in 6.

The bad break in John under discussion today comes in 20.29/30.  Most of the time John 20:30-31 are separated as a "conclusion" to the book.  However, what if these verses are a conclusion to Jesus' words in 20:29? In that case Jesus' beatitude "Blessed are the ones believing but not seeing!" is an invitation to the gospel's audience who have heard, but not seen the signs, "These signs have been written so that" in my words, "you might be one of those believing but not seeing." In a more anecdotal phrase, All this stuff you've just heard about has been told for one reason and one reason only, so that you can believe.

The question becomes how does John 21 fit?  One way it fits is the use of "after these things Jesus" as it appeared in 3.22, 5.14, 6.1, and 7.1.  The phrase "after these things" also links directly back to the discussion in 13.7 with Peter over the washing of his feet.

So, how should 20:30-31 be read?  Should it be read as a first conclusion to an earlier edition of the Gospel with no reference to the rest of John 20? Or is it possible to actually read it without any break between 29 and 30?

The real question is how many other passages in the Bible are crippled because of a bad break?