There's a happy medium between getting a job done and applying theorums/bigO/fancy data structures all the time. Probably what you came across and subsequently

There's a happy medium between getting a job done and applying theorums/bigO/fancy data structures all the time. Probably what you came across and subsequently optimized was an implementation of the former. Fun fact: Just getting the job done works out well most of the time, technical debt is introduced but as in your example it served its purpose.