It is plenty. Except, of course, when it's not.
The "typical" self-defense shooting is often described as three, threes. It's over in 3 seconds with 3 shots fired and takes place inside 3 yards. Of course, some shootings aren't typical. There's no way to know, in advance, whether you'll get a typical one or not.
That said, there are plenty of people who rely on and have successfully relied upon 6 shot revolvers for carry and home defense. If you are comfortable with the gun and shoot it well, it's not a bad choice, in my opinion.