For my side project where uptime doesn't really matter but the codebase is quite huge (gamedev of a multiplayer game with Bevy, so both server code, game code, content build pipeline, as well as a TON of editor and authoring code, probably 150k+ LoC), I've been moving towards just reviewing boundaries between modules, APIs, and schemas, and I'm pushing towards keeping things as modular as possible. If something ends up wrong, it going to be isolated and it doesn't infect the rest of the codebase. Every now and then I zoom into a module and tidy it up (or even rewrite it).
I wouldn't dare doing this "carelessly" for anything where people other than me actually depend on it, but you can move very fast while doing it and the risks with bad code is quite hedged. Different modules can mature at different rates when it becomes necessary.
Maybe not related to all of what you were saying, but I think this enables scaling without ending up with progress grinding down to a halt due to shitty code.
This can easily lead you down a path of excessive modularity with each module being excessively complex though
I have home projects like this too, and those techniques can make things well, it can also rabbit hole in ways that are less productive sometimes. I’m constantly trying to push my comfort level and find what I can delegate and what I need to specify, esp around structure and isolation.
My comment is more for the people in charge of or working on software teams on complicated products for customers - so many leaders quite a few engineers have utterly drank the koolaid and pushed maximizing AI use with zero regard for quality or even medium term effects. Many of them are getting promoted by other clueless management for it - when someone is handed a huge check for being optimistic, they tend not to second guess themselves.