Facebook sometimes does a good job of explaining its privacy policy changes, but it can also mess this up — and it’s aware it occasionally deserves criticism about the frequent shifts.

Asked during a public Q&A today on why the company does so many privacy policy updates, CEO Mark Zuckerberg said that the diverse ways people use the service, which involve many different kinds of “sensitive” private information such as us physical location, requires Facebook to be careful about its policies.

Zuckerberg said that one of the biggest challenges Facebook faces as a business is that it has grown from a simple service to one people use in many different ways. It’s no longer just a social network for sharing photos.

With people sharing vast numbers of videos, posting increasingly from mobile phones — with 700 million people using Facebook on mobile devices every day — and using it to organize serendipitous meetups, and much more, it’s essential that users understand what the privacy policy is, Zuckerberg said.

Facebook tries to update the policy once a year based on new technology and “product challenges,” Zuckerberg said. But, he added in summary, the massive growth of the service has required many changes to the policies.

“We can’t just start building a product without a policy that discloses clearly what we’re doing with [users’] information,” he said.

As a result, he said that it’s a big task to read through the Facebook privacy policies, and the company wants to take “one moment a year” to make the formal changes. “Sometimes we do a good job” with the messaging, and “sometimes we don’t, and we get criticized, and rightfully so.”

But, he argued, whatever the company does with its privacy policy messaging is “coming from a place of trying to make the product better.”