I spent the past weekend running a head-to-head experiment: five popular prompt engineering patterns, one real model (Claude Sonnet 4.5), fifty real movie reviews. The goal was simple — find out which technique actually delivers the best results. The result? The simplest approach won. And the most sophisticated one — Chain-of-Thought — didn't just underperform. It actively made things worse. Here's what happened. The 5 Patterns I Tested 1. Zero-Shot Direct instruction, no examples. Classify this movie review as 'positive' or 'negative'. Reply with only one word. Review: "The food was terrible but the service was great." Enter fullscreen mode Exit fullscreen mode 2. Few-Shot (k=3) Three input-output examples before the query. Classify movie reviews as 'positive' or 'negative'. Reply with only one word.…