There can be no definitive answer to your question but of course some "thumb rules" are applicable. * The nature of your "system" defines how much attention yo

There can be no definitive answer to your question but of course some "thumb rules" are applicable. * The nature of your "system" defines how much attention you should pay towards futureproofing. If it is an end-user app/feature only do what is required and nothing more. You are solving one instance of a (maybe) small class of problems. The future will dictate what needs to be added/modified/refactored when you reach that point and not before i.e. no predictions unless you know the domain well. * If you are building an "architecture" component like OS/Framework/Library etc. then you need to pay attention to generality and extensibility and design with futureproofing in mind. Use standard best practices like data/api versioning, narrow module interfaces, information hiding etc. * Always focus first on Readability and Maintainability to the exclusion of everything else. Only when you hit a wall with respect to aspects like Performance etc. do you go back and redo/refactor the code for the newly prioritized requirement.