SEVENTY years was spoken of by Jeremiah as the time the kingdom of Judah would be carried away captive to Babylon. He didn't use "threescore & ten" -- it's spelled out instead: s e v e n t y. "For thus saith the LORD, That after seventy years be accomplished at Babylon I will visit you, and perform my good word toward you, in causing you to return to this place." Jer29:10.
Those who heard these words would likely have said: But that's a lifetime!

Because those Hebrews returned (miraculously?) after 70 yrs., we can have confidence that the Lord will be returning for us at the time appointed. It's a parallel to the time when the Children of Israel waited impatiently at the foot of Mt. Sinai for the return of Moses after 40 days. In the meantime we're supposed to settle in and occupy the land, and concentrate on eating the True Bread of Jesus, instead of the unholy junk from the worldly table rated "R".

The seventy years in Jeremiah is spelled out--it's different from the three-score and ten of Psalm 90, meaning we have two different ways of understanding this time span. Granted, the years of the seventy are different from the centuries of the threescore and ten, yet they fit a common pattern. The rituals and fixtures of the Old Testament conformed to "the patterns of things in the heavens", Heb9:23.

Like shadow pictures on the wall and seeing through a veil (or vail) dimly, they didn't see the hands and face plainly, because God intended for his Word to include these mysteries and secrets. The Lord's House built by Solomon, 1K6:2, was sixty cubits long by twenty cubits wide, and a ten cubit porch. Just another variation of threescore and ten.