I have always had this half-baked thought that Jesus is going to come back right at a time when everyone left on the earth is at their weakest point in their spiritual walk, and therefore, it would be the test of all tests.
I understand that the Bible warns of impending doom and disaster as sign posts for the last days, but in my Christian school, our teachers pointed out that all the same signs ("wars and rumors of wars", etc.) were happening back in Jesus' day and because of this, his disciples thought He was going to come back in THEIR lifetime. (I'm not saying for certain that all of Jesus' followers believed this, I'm just repeating one of the discussions that came up.)
The Bible reminds us that even before the Flood, people were eating and drinking and carrying on, because they expected life to go on as they had known it. They had no idea the Flood was coming, even though they were warned. And the Bible also says that in the end times, two workers will be working in the field, and one will be taken, while the other is not. In other words, people will be carrying on as if tomorrow will again be just another day, just as they did before the Flood.
I personally believe that Jesus will come back at a time when absolutely no one expects it, and each person is going through their own greatest spiritual test. For some people, this might actually be a time of prosperity or great influence and success.
Even the Biblical giants of faith usually stumbled the most when things were going WELL for them, and not falling to pieces. At a time when kings were usually out to war, David was out prowling around watching women take baths, which eventually led to covetousness, adultery, and finally, murder.
Gideon, who originally told God he was from the smallest tribe and the least of his fellow brethren, became entangled in pride when God empowered him, and eventually asked the people for their gold jewelry, with which he made an ephod that the people then worshiped as a deity.
Solomon was granted everything a human being could have asked for, but fell into idolatry by the hundreds of wives that God told his kings never to acquire (Deuteronomy 17:17 -- "Neither shall he (the king) multiply wives for himself, lest his heart turn away.")
For some, times of trouble might be their greatest test, either pushing them toward God or bringing out the hardness within their hearts that causes them to turn away.
But for others, I truly believe it could very well be that their biggest test is when their lives are at an all-time high, because the good times are often when a believer forgets God and takes the credit for his or her "own" accomplishments.
I know some Christian brothers and sisters believe that if a person is truly saved, they will still be so, even if they should die at a moment when they aren't following God (what if David would have died right after wooing Bathsheba and killing Uriah, but hadn't yet repented -- would have have gone to heaven?) But for those who claim the faith but aren't truly saved or, if it IS possible to fall away from God... Their biggest temptations might occur during what seems to be the most prosperous and enjoyable times of their lives.
Of course, this is all just my own speculation -- I am NOT in any way saying that this is how it will all happen, but I've just always thought that if God said no one knows the hour or the day, the end will come at a time when absolutely no one on earth is expecting it, whether the circumstances in their lives are currently good or bad.