> If you’ve never read Fred Brooks, I’d recommend it. The aphorism is a bit dated but rings true: you can’t add another developer and make the process go faster.
He didn’t say that. He said adding developers to a late project makes it slower, explained why, and even added some charts to illustrate it. The distinction matters.
By your interpretation, no company should have more than a few developers, which is obviously false. You can argue team organization, but that’s not what Brooks was saying, either.
On top of that, parent never said he hired 40 devs for one project at one time. He was talking in general terms, over the course of years, perhaps in multiple companies.
Finally, let me invoke another aphorism: hours of planning can save you weeks of development. Right here you have the bottleneck staring you into the face.
Of course it’s development. And unless you’re in a really dysfunctional environment, most of that development is coding, testing and debugging, where AI can help a lot.
> He didn’t say that.
Actually he did, or something very close to it.
Obviously SOMETIMES you can add more developers to a project to successfully speed it up, but Brooks point was that it can easily also have the opposite effect and slow the project down.
The main reason Brooks gives for this is the extra overhead you've just added to the project in terms of communications, management, etc. In fact increasing team size always makes the team less efficient - adds more overhead, and the question is whether the new person added adds enough value to offset or overcome this.
Most experienced developers realize this intuitively - always faster to have the smallest team of the best people possible.
Of course some projects are just so huge that a large team is unavoidable, but don't think you are going to get linear speedup by adding more people. A 20 person team will not be twice as fast as a 10 person team. This is the major point of the book, and the reason for the title "the mythical man month". The myth is that men and months can be traded off, such that a "100 man month" project that would take 10 men 10 months could therefore be accomplished in 1 month if you had a team of 100. The team of 100 may in fact take more than 10 months since you just just turned a smallish efficient team into a chaotic mess.
Adding an AI "team member" is of course a bit different to adding a human team member, but maybe not that different, and the reason is basically the same - there are negatives as well as positives to adding that new member, and it will only be a net win if the positives outweigh the negatives (extra layers of specifications/guardrails, interaction, babysitting and correction - knowing when context rot has set in and time to abort and reset, etc).
With AI, you are typically interactively "vibe coding", even if in responsible fashion with specifications and guardrails, so the "new guy" isn't working in parallel with you, but is rather taking up all your time, and now his/its prodigious code output needs reviewing by someone, unless you choose to omit that step.