Maybe it would help to go back to the purpose of the "70 sevens" as explained to Daniel.
Daniel 9:24
Seventy weeks are decreed for your people [The Jews] and your holy city [Jerusalem] to:
1) restrain transgression
2) end their sins
3) blot out iniquities
4) atone for iniquity
5) bring in everlasting righteousness
6) end the vision & prophecy
7) anoint the most holy
There was a specific timeframe to accomplish these specific tasks. So the question is, where these tasks accomplished in the specified timeframe?
Well, the Messiah accomplished his part (tasks 3-7), but the people didn't accomplish theirs (tasks 1&2) and instead killed the Messiah.
For context, Gabriel was answering Daniel's prayer after studying Jeremiah and learning that Judah would be in punishment for 70 years for their sins. He was praying for forgiveness on behalf of his people to turn the punishment around. But Gabriel was explaining to him that it would be 7 times longer...and not only that, it would end with their utter destruction.
We read in Leviticus 26 that even while in a punishment, if the people continued to sin then it will increase 7 times in length and intensity...and if they continued in sin then 7 times more.
So a "70 year" punishment grew to "70 weeks of years" because they were (assumably) still sinning while in exile. And knowing this was a punishment they were already in the middle of helps put the "70 weeks" in perspective.
The "70 weeks" was a countdown for the Jews to complete all 7 tasks else they'd make their punishment worse. So we can safely assume if they had completed all 7 tasks they never would've had their city destroyed and been rejected...but that was also prophesied to be their end.
Paul explains in Romans 11 that after rejecting the Messiah the Jews were blinded and themselves rejected, and so salvation went to the gentiles. The Jews fell into an even more severe punishment, which suggests the prior probationary period of 70 weeks was over...not paused.
So if we say that the countdown was paused between the 69th and the 70th weeks, we're saying the Jews' probation - until a more severe judgment - was also paused...but this is completely opposite from what history has shown has happened to them since their rejection of the Messiah.