The project I’m currently working on is getting close to 60k lines of code, with fairly complex business logic. From what I’ve heard, at this scale only a few tools (like Claude’s desktop app) are genuinely helpful, so I haven’t experimented much with other AI coding services.
At the same time, I keep seeing posts about people building 20k lines of code and launching a SaaS in a single 40-hour weekend. That’s made me question whether I’m being overly cautious, or just operating under outdated assumptions.
I already rely on AI quite a bit, and one clear benefit is that I now understand parts of the codebase that I previously wrote without fully grasping. Still, at my current pace, it feels like I’ll need several more months of development, followed by several more months of testing, before this can become a real production service. And that testing doesn’t feel optional.
Meanwhile, products that are described as being “vibe coded” don’t seem to be getting particularly negative evaluations.
So I’m wondering how people here think about this now. Is “you don’t really understand the code, so it’ll hurt you later” still a meaningful criticism? Or are we reaching a point where the default approach to building software itself needs to change?
I’d especially appreciate perspectives from people working on larger or more complex systems.
They care about the business. If you want to be like them, start by caring far less about the actual code or how it gets made. They will bring in people later who do, who will clean up the vibed mess
*I'm generally not a fan of this, but you asked
What's cool about this is that, every time new engineer joins this wave, there are more interesting ideas coming and shaping the "vibers" industry.
In my day to day job, now I am worried, it will be very difficult to get a new job, because I vibe so much that I almost forgot to write code from scratch.
Examples:
* Hey Claude, increase mem usage from 500Mb to 1500Mb in production - fire and forget
* Plan mode: What kind of custom metrics can we add to Xyz query processor? Edit mode: add only 3,4 and 9. Later we will discuss 8
* Any other small changes I have...
I primarily became a manager of bunch of AI agents running in parallel. If you interview me and ask me to write some concurrent code, there is a high probability that I will fail it without my AI babies
What actually happens is tiered understanding. I might vibe-code a utility function (don't care about implementation, just that it works), but I need to deeply understand data flow and business logic boundaries.
The 20k LOC weekend SaaS stories are real but missing context. Either the person has deep domain knowledge (knows WHAT to build, AI helps with HOW), or it's mostly boilerplate with thin business logic.
For complex systems, the testing point is key. AI generates code faster than you can verify behaviour. The bottleneck shifts from "writing code" to "specifying behaviour precisely enough that you know when it's right". That part isn't going away.
The people I see struggling aren't the ones who don't understand their code - it's the ones who don't understand their requirements.
I should also consider isolating the custom logic in the existing codebase as much as possible, converting it into general logic, and then testing the “vibe” approach directly.