I wonder what you might think the reason is that the Lord has tarried for so long. I know that God sees time differently than we do and that He is long suffering and patient. During the last two thousand years each generation has had earnest students of the Word who have believed His coming was imminent. There have been countless “badboys” who were seen as potential Anti-Christs. As these seasons of expectation have come and gone it has left many discouraged and reluctant to continue to hope for a future date of fulfillment.
The Lord has tarried so long because the “full number” of Gentiles God already knows will be in the Church is not complete yet (Romans 11:25). With the phrase “full number” Paul was using the example of a ship not being able to set sail until the required number of crew were all aboard. When that number is reached the Church will disappear (1 Thessalonians 4:16,17).
You’re right, there have been several partial fulfillments of certain end times prophecies in the past, but before 1948 an essential component was always missing, and that’s the presence of a Jewish state in the promised land. The fatal error of past generations lies in the failure to understand that until all the prophecies can be fulfilled then none of them can. Rather than being discouraged by their failures, we should learn from them and study the prophecies more diligently.