As others have mentioned, failures happen. I found an old picture of the Lycoming IO-360 that was in our 1971 Piper Arrow. There were about 200 hours SMOH and it was running fine until it didn't. Without warning just after levelling off at 7,000 ft. it let go.
In the picture you can see the end of the connecting rod with a bolt missing and it looked like that bolt broke as we found part of the bolt in the crankcase. What you can't see is the other side of that rod where it broke with the end cap still attached to the broken part of the rod.
My partner Don was flying it at the time and he was working on his Instrument Rating with his instructor on board. The windscreen was completely covered with oil so he could not see anything in front of him-only a little out the side window. He continued to fly the plane and landed in the sage brush about 7 miles Northwest of KCPR(Casper, WY) with minor damage to the airframe. Other than the engine and prop which was damaged by metal from the engine coming apart, the only damage was one linkage arm that was torn loose from the main gear to a fiberglass landing gear cover. N1939T flew again about 9 months later.