At work there’s been a huge number of duplication in the start of the company and no solid abstraction. So no tests as well. We introduced tests in the current architecture but rewriting code has a huge cost to make sure there is no regression. When we talk about a saas it’s non-trivial with many customers relying on this tool daily as part of their workflow, regressions because of rewrite could be really painful for them. So we must give a greater budget to take the time to make sure nothing major breaks. So there is a debt that is compounding over time because code is added. Duplication is bad and weird/purist abstraction could make the architecture so rigid that rewriting things could generate hard to understand and catch bugs. It’s hard to find a good balance and it depends on the kind of business and scale of project. Hard to make that a generic advice.

I think all these comments here are kinda talking past each other.

It all depends on the amount of duplication and the complexity of the abstraction. Like you said, no generic advice is possible that clearly separates it into "abstract here" and "duplicatehere".

In your example it sounds like we aren't talking about 2-3 places where duplicate code existed that just needed to be refactored into separate units. It sounds more like a complete disregard for abstraction to move on quickly.

If you see duplicate code and have a good understanding how to solve that then it's totally a good thing. The real problem comes in if you add abstractions without knowing wether they will hold up. And this is where the blogpost comes in. In my opinion 2 duplicates are fine, at 3 you should start thinking or implementing an abstraction if you have a good understanding of the code and usecases.

"It’s hard to find a good balance and it depends on the kind of business and scale of project".

Exactly. The abstraction purists are not working in the messy, dead line driven real world.