A term with strong connections to OnceAndOnlyOnce: Name and Conquer: introduce appropriate terminology to reduce complexity of expressions/code, including new variables, changing variables, introduction of new functions.
"The normal way to avoid redundancy is to introduce an identifier[1]. As its name suggests, an identifier names, or identifies, (the value of) an expression. We can then use its name in place of the larger computation. Identifiers may sound exotic, but you're used to them in every programming language you've used so far: they're called variables. We choose not to call them that because the term 'variable' is semanticallycharged: it implies that the value associated with the identifier can change (vary)."
See also WikiWordsAreConcepts, DivideAndConquer, OnceAndOnlyOnce, NameMagic
Related: NamingConqueredLands