Vocal warm-ups are a near-universal feature of secondary choral rehearsal, making it important to understand how they are structured and adapted within the routines and constraints of classroom practice. Prior surveys tend to (a) treat warm-ups as one item within broader pedagogy instruments, (b) sample singers rather than educators, or (c) test warm-up protocols experimentally with single ensembles, leaving limited national, educator-reported data of how secondary directors design, sequence, and adapt warm-ups under real classroom conditions. This study reports on a national survey of 154 middle and high school choir directors, offering new large-scale, practitioner-focused data on how educators shape warm-up routines and the factors that guide those decisions. Results highlight the primacy of vocal health and technical development, the influence of inherited traditions and teacher preparation, and the relatively limited presence of student choice or emerging tools such as real-time audio visualizations. Findings suggest that warm-ups persist as both protective rituals and pedagogical habits, anchoring technique while reflecting cultural and institutional continuity. While warm-ups are sites of technical preparation, they may also hold untapped potential for cultivating student agency and motivation. Implications for practice center on aligning warm-ups with recent findings in voice science, established and emerging technologies, and exploring how warm-ups can foster student autonomy and group cohesion without losing their grounding in vocal efficiency.