Judges 12 records the names of several judges, including this lesser known judge,

After him, Ibzan of Bethlehem judged Israel. He had thirty sons. And he gave away thirty daughters in marriage, and brought in thirty daughters from elsewhere for his sons. He judged Israel seven years. Then Ibzan died and was buried at Bethlehem  (Judges 12.8–10).

He judged Israel seven years, but there does not seem to be any significance to that amount of years, because other judges were over Israel for different amounts of time, and the Bible does not attach any meaning to the number of years they judged.

Therefore, we conclude that Ibzan’s time of seven years as a judge was merely incidental.