So in a way, this "12 Strong" strategy has been a big gamble.
Look, we don't know how many ninjas the proctors intend to advance from this exam, but my guess is that it's a major winnowing device. Eaglejarl said outright that at least half the teams have been straight-up "taken out" and then you have the ones who don't bring in enough seals. I wouldn't be surprised if they only end up advancing 32* or so (10%) and then those go to the tournament. 32 would produce five rounds of tournament fights, which would allow everyone to display their stuff. That's 11 teams. We want to ensure the pass of 4 out of only 11 teams?
*11 teams would be 33, but I'm sure they can just pick the two weakest-seeming ninja and force them to fight for a slot or something.
Or hell, what if they only take the top fifteen and then it's a four round tournament, with some lucky fellow getting a bye on the first round! Then we're trying to ensure 4 out of only 5 teams!
I can see why multi-team teams might not have been a popular strategy. If you're trying to provide enough seals for 12 people to advance, you have to give up all hope of just targeting the weak and mutually agreeing not to fight with the other strong. It becomes not doable anymore. You're going to have to fight the strong. The numbers ensure it.
That was always going to be a tough row to hoe. We just did the easy part, chilling in a fort and relaxing for the majority of the exam. Boosting our score with seals. But now the piper comes due. We are going to have to fight multiple strong teams to win this. The best of the best, the few out of the 300 with the most power and skill. It's going to be brutal. And frankly, running around hunting a few weak teams won't help much. It's the toughest ninja that have the number of seals we need if we want 12 people to all pass.
Now, our advantage is that we do have numbers and we did spend most of the exam relaxing in the fort. Tanned, rested, and ready as the saying goes. But this is going to be one hell of a punch-fest.