Even considering a lower rate of production (say 50% of that figure, still puts a force a quarter the size of the United States Army's front-line troops in the suburbs of Boston. That would be an absolutely immense occupation force, even for modern-day Boston. Greater Boston has under 5 million people. That's 1 synth for every 50 persons. To put that into perspective, post-war Japan was occupied to a level of 200 to 1. Post-war Germany had a ratio of 80 to 1. Now it's quite reasonable to say that no matter what the condition of the commonwealth might be, it's got to be less than the population of Greater Boston today. This really underscores Balmas' original point: Given the capacity of the Institute to produce manpower, it's really inane as to why they simply can't produce enough Synths to take active control of the surface, not just in the Commonwealth, but likely the entire continent of North America. That 'one per 25 minutes' facility is just one relatively small room. Conduct synth production at industrial scale, and they could easily conquer the surface and re-populate the continent with genetically healthy, docile and obedient humans. Instead, they're doing some kind of Dystopian Doctor Strangelove freak lair.