Dr. Scott Hahn has pointed out the significance of “seven” in regards to covenants. I’ve heard him mention it on TV within the last two months or so, on some program.
He’s not the only one to mention the occurrence of “seven” either literally or by refernce. I just read something about St Paul’s epistles, and the writer mentioned that Paul wrote epistles to seven named groups (Ephesians, Philipians, Corinthians, Romans, etc.) and that there are seven churches mentioned in the Revelation of St. John.
In a Jewish commentary which discusses the number seven used in the first creation account in Genesis, there are not just seven days for creation, but the verses there either have seven Hebrew words in them or a multiple of seven words.
“Three” has associated with the three Persons of the Holy Trinity, for example. “Twelve” has the tribes of Israel and the number of apostles associated with it (although there were more than 12 of each).