In my Factorio and Satisfactory play-throughs, I almost always end up building factories that are a spaghetti of conveyor belts, with no overarching clear structure. I get better at it every single play-through though, but there nonetheless will be a point where everything breaks down.
I have a good strategy for early- to mid-game. The factories I build there are clean, neat, organized, efficient, modular, extensible. At the late-game stage, however, I don’t have a good strategy, and the factories I’ve built aren’t sufficient anymore, and I start hacking around to fit new production lines in.
This is eerily similar to how tech debt in software development is created.
There are two reasons why good Factorio intentions can lead to a chaotic factory nonethless:
There is a resource (power, or a constructed part) that you need right now before you can continue. You’ll end up creating a small quick-and-dirty factory setup, somewhere off the side, that creates that resource.
An existing factory setup isn’t able to produce resources to keep up with the demand. You’ll shoe-horn in more assemblers and belts, and in the process you’ll make the layout of that existing factory setup worse. This happens because space is limited and belts have limited throughput.
Once the chaos is too big, you have two choices:
You can start a new game. This doesn’t solve the problem in the current game, however, and chances are that you will run into the same problem again in your new game.
You can refactor.
Refactoring is the only sustainable choice. If you start a new game every time you have created a mess, you’ll likely end up abandoning Factorio altogether.
Refactoring in Factorio is generally easy. There usually is little preventing you from wiping out an entire part of a factory and starting over. The only exception is the infrastructure that keeps the hostile alien lifeforms at bay — you’ll have to be more careful to keep that running.
As for how to refactor… that’s another story.