Brent Ozar recommends some actions:
You were minding your own business, and all of a sudden it happened.
You glanced at file sizes one day, and your eyes got big. The numbers got a little large while you weren’t looking. This is a great time to stop and think about a few changes to the way you’re managing this database.
These are some good recommendations on the whole. 1TB isn’t a magic number, but it’s a pretty decent dividing line.