[allengeorge]

Only in the most trivial cases.

Most systems I've worked on have some overriding architecture and assumptions. The worst quality erosions happen when changes are shoehorned into the code without a complete understanding of those factors: it's likely there'll be semantic mismatch between the new feature and existing components, unexpected bugs, and harder to modify code (because the overall architecture is no longer coherent).

You can mitigate the disintegration by having a maintainer with a strong understanding of the architecture and the problem(s) being solved by the original system. Talking with them can give you a roadmap on how to modify it properly, and if it's even possible to do so while maintaining architectural and design coherence.

Note: my comment is an opinion based on personal experience. I'm not trying to play it off as fact.