Any approach to representing a complex problem or system in code,is like any tool - only as good as the person using it. Given a really complex problem domain,

Any approach to representing a complex problem or system in code,is like any tool - only as good as the person using it. Given a really complex problem domain, functional decomposition and data modeling have their own issues. Other than an object-oriented approach, what else is left? Constant experimentation with procedures and subroutines until anything that can possibly work is discovered?