One of the biggest mistakes I continue to see in software development is leaving too many options open for too long. It seam that many designers/developers try to build-in future-proofing by including config-ability and constructing as open-ended a solution as possible, which becomes virtually impossible to test. I would argue, a better approach to enabling future-development is to do the minimum and keep the implementation as specific and tight as possible. This enables concise testing and controlled enhancement as future needs become apparent. This touches on the KISS, DOT and “Start small and iterate” principles.