Why is 'Seven Years' Not Mentioned in the NT?

Bible Prophecy Under the Microscope-Episode 104 Gary does a deep dive on the absence of a seven-year period discussed in the New Testament, which is crucial for many end-time theories. He asks why, if this timeframe is so pivotal, it is not explicitly mentioned in the NT. Although "three and a half years"  are mentioned in Revelation, the concept of a definitive seven-year tribulation is not.