Curate, connect, and discover
I highly encourage turning on the tumblr setting for showing timestamps on posts and replies. It helps keep things in context. It's really easy to feel overwhelmed when you see post after post of bad news with no reference to when it's happening - there's a sense of urgency and panic because it all seems current, even if logically you understand that there's lots of post churn due to the nature of the queue/reblog system.