When we studied the daniel book I also used the perpetual calendar to check all the dates around that time of 1918, and the conventions and other things they claimed to see if any of the dates matched up. Absolutely nothing matched. You are right, who ever writes this stuff never checks it out. They even tried changing it around a little later on and still did not get it right. They also try to use the 360 day to get their days from the bible but then they count the days with our modern calendar which has been proven to be off as much as years. The whole thing was dreamed up by rutherford . He just figured that the jws believed every thing else, why not this . He probably figured no one would check it out.
I told my wife that any religion could say the same thing. Just have some conventions, write books, phamplets, etc. so that they would match certain dates and then claim that it fullfilled the days in the bible. That is exactly what rutherford did. The problem is rutherford must not have been able to count.
If the idiots at bethel would reserch this crap, they would probably just quit putting it in the literature, other wise they have to be doing it knowing it is wrong.