The Society is wrong to make it mandatory for JW's to preach in a door-to-door, house over house style (only the very elderly and sick aren't expected to do this). It is especially lamentable that some JW's have been imprisoned and worse for refusing to perform this activity, believing that it was literally what the first century Christians did.
That said, Ray Franz's research in ISOCF doesn't prove that the first century Christians DIDN'T actually preach in some kind of house over house style. They may have or they may not have. The point is that JW's should have more freedom of choice in the matter.
I think Ray Franz does well to highlight that the Society have abused the 'house to house' concept, but there are weaknesses in his argument against the Society on this point. His claim on page 214 of ISOCF about the 'distributive' sense of the preposition kata not being the same as 'consecutive' is not sufficiently elaborated on. He fails to provide any examples or authority that demonstrates that for 'katoikon' to be rendered 'house to house' it must necessarily have a 'consecutive' sense. In fact, Franz does not give one example from the bible of a 'consecutive' sense meaning of kata and how this can be contrasted with the 'distributive' sense in an ancient context. Instead Franz has to resort to a modern-day analogy about a doctor making 'house calls'. Not very scholarly.
When you research things a bit more you will find that a 'distributive' sense has a more defined meaning than "going from a home in one area to a home in another area, just as a doctor making 'house calls' might go from home to home" as Franz portrays (p.214). For examle, R. C. H. Lenski, in his work 'The Interpretation of The Acts of the Apostles', Minneapolis (1961), makes the following comment on Acts 5:42: ‘Never for a moment did the apostles cease their blessed work. "Every day" they continued, and this openly "in the Temple" where the Sanhedrin and the Temple police could see and hear them, and, of course, also [katoikon], which is distributive, "from house to house," and not merely adverbial, "at home." This quote from Lenski is found in a footnote to the NWT reference bible but Franz doesn't address the point.
Franz fails to deal with the fact that when the distributive KATA is used, the idea of repetition is involved, usually with reference to people, times, or places. The word "every" is a good word to use in reference to this preposition. In the case of Acts 5:42 and 20:20, this was not necessarily in the methodical, 'house-over-house' style that JW's perform today when walking down a street, but it seems clear that the disciples tried to distribute their message to EVERY household in whatever town or village they went to. Given this clear point, it would seem illogical that the disciples would waste energy and resources by making doctor-like 'house calls' going from one area to another in the way Ray Franz proposes. I think they must have had a more systematic approach than that, but not necessarily as systematic as the JW method.
Here is some research on 'kata' from a relevant website:
Distributive KATA
Greek prepositions usually merit their own major section of discussion in the syntax of most Greek grammars. They merit such discussion due to their multifaceted nature. The Greek preposition is one of the Swiss army knives in the Greek language; one preposition may have multiple uses. The Greek reader must carefully consider the context in which the preposition is used and correctly apply the proper usage if he is to get all there is out of reading the text. In our discussion this week, we will look at one particularly special nuance of the Greek preposition KATA.
KATA may take two cases depending upon how it is used. With the genitive case, KATA can mean "against," "down," or it can intensify the meaning of something as to it's depth (such as in 2 Corinthians 8:2). With the accusative case, KATA may represent ownership, authorship, or repetition (distribution). It is sometimes translated "according to" with this case. It is the last use of KATA, the distributive use, which we will focus upon here.
When the distributive KATA is used, the idea of repetition is involved, usually with reference to people, times, or places. The word "every" is a good word to use in reference to this preposition. For example, in Matthew 27:15 (and in the parallel in Mark 15:6) we have the distributive use of KATA. The ASV text says, "Now at the feast the governor was wont to release unto the multitude one prisoner, whom they would." The word KATA occurs early in the sentence. It is translated here by the word "at." However, when taking the distributive use of the preposition KATA into account here, we would more accurately translate the sentence, "Now at every feast…." The idea is that this was a repeated event. That it wasn't just at this feast, but was customary at all of the feasts to release a prisoner.
Another rather obvious example is in Mark 14:19 where the disciples question Jesus "one by one." The word translated "by" in this verse is KATA. The distributive sense can be seen clearly in this passage.
Romans 12:5 is also another good example. "So we, being many, are one body in Christ, and every one members one of another." Each individual member is part of the body of Christ.
Perhaps one of the most significant uses of the distributive KATA is found in 1 Corinthians 16:2: "Upon the first day of the week let each one of you lay by him in store, as he may prosper, that no collections be made when I come." You may think that the word "each" in this verse is KATA, but it isn't. The word KATA is translated "upon" in this verse. The idea is upon every first day of the week, the church was to take up this collection. The implication is obvious. The church met every first day of the week and this was the time at which Paul instructed them to take up their contribution.
Other examples of the distributive use of KATA can be found in Luke 8:1, 4, 9:6, 13:22, Acts 8:3, 13:27, 15:21, 15:36, 17:17, 20:23, 22:19, 24:5, 24:12, 26:11, Titus 1:5, Hebrews 9:5, and Revelation 22:2. A good exercise would be to see if you can spot the distributive KATA in these verses.