Should I use default/untouched metadata or manual?

Is it better to leave post metadata untouched? I run a news site, and if entering manual metadata for posts is going to detract from Google’s ability to crawl and do stuff automatically, then I need to make changes to my strategy.

So far, some of our posts show up on Google, but others—including our most-read story so far—do not.

I’ve been entering metadata manually (including for the aforementioned story), but for newer stories I’m testing to see if leaving it blank will help it show on Google faster.