Competing theories don’t do much to define the great tribulation or the event that triggers it—the abomination of desolation. The Peri-Armageddon scenario clearly defines both.
The Bible foretells a man standing in the holy place of the Jewish temple (to be built in the years of the next great peace), claiming to be God and receiving worship, (2 Thessalonians 2:1-4). Of things foretold, yet to come, what could be more abominable than this?
The natural consequence of this abomination will be a global society that is desolate of godliness, as God-fearing folk of all sorts will be forced into voluntary exile (bug-out) or martyrdom. Furthermore, I think this depraved society that is willing to worship a man and take the mark, that God will supernaturally strip from their hearts and minds every single fruit of the Spirit as listed here: “But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, Meekness, temperance: against such there is no law” [Galatians 5:22-23]. The marked may be able to squeak by for a little while in a state of denial, briefly satisfied with earthly pleasures and coping mechanisms; but their demise shall be rapid, and after only a handful of weeks of trying to fool themselves, mutually assured destruction (M.A.D) starts to look like a viable option for them.
On the day that the abomination of desolation occurs, the great tribulation begins.
For those who will not bow or take the mark, (very wise), the alternative is plain and clear: bug-out (evacuate society in haste) or face incarceration and martyrdom. On day 45 of the great tribulation (Daniel 12:11-12), a major blessing occurs for those who evacuated or took flight from society. I believe that plague #5 (Revelation 16:10) will afflict those with the mark to such a degree that survivors can walk into town on that day to replenish their survival supplies and gain a second wind. (For some detail on Plague Five, or any of the plagues, also read “Plague Seven & the Angels’ To-Do List”).
By the time plague #5 wears off the marked will have just about come to the conclusion that their lives are too miserable for their problems to be overcome with the coping mechanisms or the creature comforts of civilization. Suddenly, plague #6 opens the pathways to Armageddon (Revelation 16:12-16), and the prospective annihilation of all living things. Fortunately, they will not succeed at M.A.D. because Divine intervention (Matthew 24:21-22) prevents it; and the only thing great enough to distract them from pushing the buttons releasing their stockpiles of W.M.D. is the appearance of the Son of Man, like a thief in the night, (Revelation 16:15).
So, the great tribulation is a survival challenge to God fearing folks from all cultures and backgrounds around the world, and the challenge shall remain for a period of time that extends a little beyond six weeks. Those who can make it to day 45 will have basically reached the point of no return, and it is all downhill from there. As tough as that survival challenge shall prove, the real nuts and bolts of the great tribulation, foretold to be the worst time of suffering in human history, is the toll that it shall take on the society of the marked; it will be Satan’s greatest single theft of souls in all of human history. It is their terror and suffering, not ours, that makes the great tribulation so bad.
For the theories that poorly define the abomination of desolation and the great tribulation, they can for a while get away with declaring that it shall last for 3.5 years or even 7 years, but at the end of the day, when the reality of the great tribulation becomes apparent, anything much longer than the six-week scenario would be impossible to endure. Not only would it be impossible from the standpoint of survivors in the wilderness, but even more so would it be impossible to the marked, those who have nothing of any true value left in their hearts, minds, or souls.