It's likely been mentioned in other reblogs, but this is where the queue shines! Want to reblog 50 things but without putting literally 50 posts back to back on your followers' dashes? Have other people reblogged the same post 50 times, and you HAVE to reblog it as well, but don't want to be 51?
Your queue will distribute I think it's 1 - 50 posts a day, evenly spaced. You can also schedule posts/reblogs for specific days and times - say there's a Christmas post in July. Not an ironic one, just a regular post. You might not want it in July! In that case slap a date on it and it goes in the queue for THAT DATE rather than posting at the whims of the the queue's timer.
For example, I have an ancient post of a Christmas Godzilla topiary in some Japanese mall that's consistently scheduled for December 1st.
Anyway, back to the idea of the queue one more time before I quit. The other major thing about it, in addition to managing your own posts, is that the queue is what keeps posts alive here. On every other site, a post gets its initial impressions and then it's gone. No one talks about it again once it exits the collective attention span. But the queue gives posts indefinite life. Without it, we wouldn't have our heritage posts or the Old Magicks.
People talk about how Tumblr is dying, blah blah. The queue is why we HAVEN'T died though, even through all the years of changes that should have killed the site otherwise.