I like the rule I read somewhere called Rule of 3. Goes something like, don't bother to write a shared version of some piece of code until you've already writte

I like the rule I read somewhere called Rule of 3. Goes something like, don't bother to write a shared version of some piece of code until you've already written it in at least 3 different places. This simultaneously ensures that 1. There is actually a need to use this code in multiple places 2. You know where the places that need this code actually are, and what they need, so what you write will actually be practical for all of them to use 3. Or maybe you can tell that, despite the seeming similarity, the different places are too far apart or too different for sharing code to actually make sense