While I would normally tend to agree, I have had rods fail and take out the case. I would recommend checking the lower rod end bushing before the start of a flying season for wear. If there is obvious wear that can be seen with the eye alone, change the rod. To me, this would be cheap insurance as compared to having to buy a new case or replace the whole engine. Obviously, this wouldn't apply to an engine that has bearings around the crank pin