You will often see a reference to a 70th week at the end of time "inserted" into Revelation, or Matt 24, or 1Thess 4.
None of those chapters mention a "70th week" or the "midst of the week" or any such thing.
In the bible we have these 3 rules
1. All bible timelines are unbroken and contiguous without exception. .Daniel 9:1-7 is a good example withe Jeremiah's 70 years.
2. All Apocalyptic timeline use day-for-year symbolism. Each day is one solar year.
3. Bible authors build on the previous prophetic statements of scripture.