Surgeons practice their own variations on a procedure. Residents experience shifting thresholds between variations that one surgeon holds firmly as principle and another takes more lightly as preference. Such variability has implications for surgical education, but the impact is not well understood. This is a critical problem to investigate as programs seek to define procedures for competency-based medical education (CBME) and improve learning through deliberate practice. Our study analyzes the emergence of procedural variation in an early-adopter CBME program through a situational analysis of tonsillectomy, a foundation level procedure in this otolaryngology, head and neck surgical program. An earlier phase of the study identified frequent variations (n = 12) on tonsillectomy among co-located surgeons who routinely perform this procedure (n = 6). In the phase reported here we interviewed these surgeons (n = 4) and residents at different stages of training (n = 3) about their experiences of these variations to map the relations of contributing social and material actors. Our results show that even a basic procedure resists standardization. This study contributes a sociomaterial grounded theory of surgical practice as an embodied response to conditions materialized by intra-relations of human and more-than-human actors. Shifting root metaphors about practice in surgical education from standardization to stabilization can help residents achieve stable-for-now embodiments of performance as their practice thresholds continue to emerge.