That seems excessive?. . . lol I know people older and more experienced as well as younger and less experienced than I, that have not (to date) failed a "Check ride". However, I also know people that have (without exaggeration) flunked every single check ride they have ever taken, one person in particular more than once for each rating, and is flying "professionally" today.
Just about everyone busts something.
I busted my Multi-Commercial (I still argue that I did what I was trained to do, but he said that didn't matter...and thus I took it as a lesson learned that I've carried with me to this day, passed it along to others, so it was a good thing). My record is perfect otherwise.
A lone bust is not significant. It's a trend of failure that matters.
Anyone can bust a ride on any day. As an instructor you can bust anyone who walks into that bay. But that's really not the point. We're trying to teach, not fail.