The session we played in the Lava Beds was interrupted several times. We started by rolling up characters and looking at the map of the locale. Then we explored a few caves. Then we played a few hours. We decided to break for lunch, which entailed making our way back out of the caves and driving a bit, eating, then driving back. Then we played some more.
What I noticed was that these breaks seemed to be fruitful. While walking the players were talking about what they thought of npcs and what plan of action they might take. Basically decision making and meta-game talk that always happens, but here it was happening away from the table, explicitly out of game. And what that meant was that when we got back to the game players went right into roleplaying; they knew what they wanted to try to accomplish, they were refreshed and relaxed from the break.
After noticing that I wondered if I might be able to build breaks into a session purposefully. This could be difficult because it seems my players generally have a total playing time limit 0f ~4 hours that we can work with. But it might still be possible to have an intermission of sorts.
What worked well in the caves was that we actually had some place physically to go. I'm not sure if it's enough to say "Okay we'll break now" and then just eat at the same table your playing at. I think it would be better to at the least get up and take a walk around the block or maybe go out in the backyard/on the balcony. It might even be good for players to get some time to chat game stuff away from the DM, but not necessarily.
So, for those of you with long running campaigns and more experience in these matters, do you ever break play? Would it be possible to incorporate a break?