Brooks covers this case himself in chapter 2. He says men and months are interchangeable only when a task can be partitioned among many workers with no communication among them, and his examples are reaping wheat and picking cotton. 100 independent attempts are exactly that kind of task. He would have agreed they scale.
But the work doesn't go away, it moves. Someone still has to judge the 100 results, pick one and integrate it with everything else. That part doesn't partition, and it's where Brooks put most of the schedule anyway: in the same chapter his rule of thumb gives a sixth to coding and half to testing.
But the work doesn't go away, it moves. Someone still has to judge the 100 results, pick one and integrate it with everything else. That part doesn't partition, and it's where Brooks put most of the schedule anyway: in the same chapter his rule of thumb gives a sixth to coding and half to testing.