[mostlylurks]

There is no need to accommodate for future usage. Most of the issues resulting from abstractions actually come from people treating abstractions as sacred, trying to adapt abstractions used by some piece of code to fit new use cases, when they should be treating abstractions as disposable instead, swapping them out and creating new ones instead of altering existing ones. If the abstraction that you come up with based on the first few examples is not suitable for new use cases, that's completely fine.

As far as generality is concerned, it's not the number of examples that matters. Once you learn to distinguish whether your duplicated code actually duplicates some piece of knowledge or just happens to resemble another piece of code by happenstance, you stop having to rely on an unreliable magic number as your limit on how many instances of duplication to allow before abstracting something. And that skill probably correlates strongly with the understanding that abstractions are not just macros that make it more convenient to repeat some chunk of code, they actually represent knowledge, and thus their primary use is not to eliminate duplication, but to encode an understanding of a problem domain into the code.