The standard for accuracy for the Hebrew prophet was 100 percent.
That is, the prophetic word, if anything other than 100 percent accurate was considered false, and the prophet became subject the the Jewish law which required that he be stoned to death.
So, the choices were simple:
Either 100 percent accuracy or death.
You can imagine the professional pressure exerted on these spokespersons. If they presumed to speak for God, and they did not do so, but spoke from their own ideas, then they were considered blasphemous and liars.
Examples of long-range prophecies:
"Abraham was told that the children of Israel would sojourn in a strange land for some four hundred years, a prediction that was literally fulfilled in the slavery days of Egypt.
Jeremiah was told that the Babylonian captivity would continue for seventy years. Daniel read the prediction and as the time for deliverance drew near, knowing that the Scriptures would be fulfilled, he set himself to seek God and to prepare for the end of the captivity.
From the going forth of the commandment to build Jerusalem unto the Messiah was to be four hundred and eighty-three years. The command to rebuild Jerusalem was given somewhere between 454 and 444. Figure out these dates and you come to the days of Jesus. It has happened exactly as foretold and the Divine prediction has been fulfilled right to the year." (Dr. Oswald Smith, 1943, Prophecy: What Lies Ahead? p. 37-38).
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Other authors that I highly recommend include:
Dr. John F. Walvoord, Dr. Charles Dyer, Dr. Dwight Pentecost, Dr. John Hagee, Dr. Tim LaHaye, Dr. David L. Cooper, Dr. Oswald J. Smith.
The current ministry of Hal Lindsey, and others like him (see the links page), is an excellent resource for our modern investigation of prophecy. Mr. Lindsey has a weekly International Intelligence Briefing that shows on various TBN channels (see his website for times per locations). His books have been on the New York Times best-seller lists for years, beginning with his Late Great Planet Earth in 1970 (the number 1 nonfiction bestseller of the 1970s).