Personally, the "Rule of Three of Software Engineering" has been a good enough practice for most cases, as usual with any rule of thumb there are exceptions but

Personally, the "Rule of Three of Software Engineering" has been a good enough practice for most cases, as usual with any rule of thumb there are exceptions but most of the time I can apply it. I've been using it for many, many years and it has saved me a countless hours by postponing abstractions, modularisation, etc. to the point where it actually emerges as a pattern in the software I'm working with. Let the code repeat itself, copy and paste, and only after some pattern repeat itself for the 3rd time I start to think on how to abstract, or modularise it. It's always so much easier to rework repeated code/patterns into abstractions than fixing misguided abstractions done too early.