I think that if your playing survivor mode in multiplayer and your team doesn't lose a single round you should be safe from losing survivors. The reason I'm thinking this is because I've got a clan where I need over 100 supplies to keep healthy, if your team has a perfect round, theirs almost no way to get the supplies you need, so because you did so good, your clan suffers, I find myself having to throw some matches jus so I can get enough parts to keep my clan alive.
If your team is just amazing then theres no reason to be afraid to let the other team win the first 3 then collect all the toolboxes and stage a comeback. That's what my posse does but we aren't little girls. Confidence in our ability rocks