In my experience it mostly just boils down to having the right processes and being strongly motivated to do things right rather than push things out the door as quickly as possible. Assuming superiors have your back, this is doable. It's when they don't or when the developers lose or completely lack motivation that things start to fall apart.

Lack of motivation often means lack of process, lack of process often means lack of testing and maintenance, lack of testing and maintenance often means lack of quality. It's a vicious cycle too - once you start down the road it's harder and harder to get motivated about your product again.

Pretty much.

Honestly, the only reason the codebase isn't a mess is its a single project I've been able to tightly control and enforce things on [because its 100% my problem if something goes wrong].

The rest of our codebase is filled with drama. :/