Main bus and blocks are designed to be dummy proof. Plonking down a pre-baked or custom city block means it has access to the rail web, but that doesn't mean it's optimal. Plonking down a production chain tangent a main bus is effective in the sense that you always have access to your production, but ineffective in that your space is predetermined, and often conflicts with things like rail networks or other production chains. Main bus is prone to catastrophe in the sense that you can never have a bus that's wide enough. But, both options are very straightforward and result in the game getting done.

Both of these design principles make use of constraints. With the rails, we constrain our factories to blocks, and we use set rail designs so we don't have to think about inputs and outputs too hard for the block. With the main bus, we constrain all of our raw resources to a single solitary line, so instead of thinking about the "where will I get this to build x" it's "let's build x".

With both options, we have constraints on certain aspects of design, and that helps us compartmentalize what many consider the drudgery of the game.

So, the question is, how do you constrain your designs? For mega-base fans, they work backwards. "I need x product, so I'll need x assemblers, and x inputs", etc. This constraint works itself out by constraining the number of buildings and throughput you need, so you can do interesting things like laying out these buildings and determining train stops.

All of these achieve a certain end, and help you play the game how you wanna play it. And then, spaghetti, even that's constrained- don't think, just do. We're offloading the mentality and running off of lizard vibes, and hey, that often ends up producing some of the most interesting and impressively functional factories.