Not sure that generalises outside of math. Is it really better to solve one problem really, really thoroughly, than to have a good-enough fix for five? Depends on the problems, perhaps - but without knowing anything else, I'd rather solve five than one.
I don't know the exact context of this particular quote, but George Pólya wrote a few books about how to become a better problem solver (at least in mathematics). In that context the quote is very reasonable.
Another month, another rationality quotes thread. The rules are: