Both. You get a better understanding of when/where to focus by understanding what the similarities and differences are between languages. I'm better now becau

Both. You get a better understanding of when/where to focus by understanding what the similarities and differences are between languages. I'm better now because I've done PHP, VB, Java, C#, Groovy, Perl, Ruby and some others, even though I focus about 90% of my time on just 2 of those areas. You get a better idea of what 'advanced' is both by diving deep in to one language but also by digging in to other languages - seeing how they do stuff, what's possible, what's elegant, what's a hack, etc.