I agree but there is a small snag in thinking the length of GT has always been the same:
Mat 24:21 For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be.
Mat 24:22 And except those days should be shortened, there should no flesh be saved: but for the elect's sake those days shall be shortened.
Let me add in what you are saying and see if this makes any sense:
Mat 24:21 For then shall be great tribulation
for three and a half years, such as was not since the beginning of the world to this time, no, nor ever shall be.
Mat 24:22 And except those days should be shortened
down to three and a half years , there should no flesh be saved: but for the elect's sake those days shall be shortened
down to three and a half years.
That isn't a shortening of "those days" of "great tribulation". Therefore, it had to have been longer than 3.5 years so it could be shortened to less amount of time.
Comment?
@Runningman