I work one room at a time for a couple of reasons.
The main reason is to make sure I get everything, I don’t want to risk having the wrecks despawn before I get them and I definitely don’t want to risk another player invading the mission site and getting the loot.
Also a lot of the missions have numerous amounts of NPC wave’s that take time to destroy. Also I usually start playing late and may not complete the entire mission before downtime. If DT hits, then that’s extra loot and salvage for me.