All submissions, all the time.
The differences between what agents want to see make the whole submission exercise somewhat slow going. For instance, I've now written synopses of varying length, from one sentence to a full page. As I get more of them done, I expect I will be able to re-use more elements.
One of the agents had an interesting request, though. In addition to the first 30-some pages, this agent asked for "one of your favorite sentences from your story." That took a bit of looking to figure out what to choose. This is the one I picked:
The living juggernaut rammed headfirst through the blackjack tables, tossing its mighty horns as playing cards fluttered like a cloud of butterflies in its wake.
I selected that because the first 30 pages are not action-heavy, and I wanted to give a hint that we get into some action down the road. Also, I like the bit with the butterflies.
Other writing churns along. I've had a lot of ideas, which is good, and now I need to get some more onto paper. The screen. Whatever.