Yeah I never thought about it like that until someone brought it up on the board a few weeks back. Knight has 5 final fours, so he's a few ahead of JB on that account.
If you look at his record though; he kinda did slow a lot at the end. His last 4 years at Indiana he won a little over 20 games per year and finished around 5th in the league every year; and went 2-4 in the tournament. Then at Texas Tech he was really mediocre as well; he coached 6 full seasons there and won 3 NCAA tournament games. So in his last 10 seasons as a coach, he won 5 NCAA tournament games.
JB had a little stretch like that; the 05-08 period where he didn't win an NCAA tournament game and missed the dance twice. But he's obviously rebounded really strongly since then.
Of course, now to defend Knight; his 75 team had a great chance at winning the title but Scott May broke his arm. So he was possibly one injury away from 4 titles. (That's more of a rebuttal to any possible comment on JB having a title won in 10 but for AO getting hurt and pointing out that it works both ways. Indiana over those 2 years lost one game total, and it was when May was trying to play through the injury. )