If you can't get a good answer with one long run, then you can't get a good answer with many short runs either. Many people reject this, giving a number of different reasons.
Many short runs can sometimes give a better answer.
Many short runs can better diagnose nonconvergence. We need some woof about diagnostics. Referees, editors, and readers demand it. Many short runs can sometimes give a better answer. This is a traditional theme, with lots of literature.