Aim: To evaluate diagnostic variability in type1 laryngeal clefts (LC1) and deep interarytenoid notches (DIN), and assess how interpersonal bias, anatomical grading, and patient-specific factors influence paediatric airway treatment decisions. Methodology: Six experienced paediatric ENT surgeons participated in a two-stage, mixed-methods study at a tertiary paediatric hospital. Stage1 presented 96 clinical scenarios varying by age, VFSS results, pulmonary complications, neuromuscular status, and intraoperative anatomy. Surgeons chose no surgery, injection augmentation, or suture repair. Stage 2 involved blinded grading of 15 sheep larynx specimens (normal, DIN, LC1) to assess diagnostic accuracy, misclassification severity, and bias. Logistic regression analyzed factors influencing treatment decisions. Results: Overall diagnostic accuracy was 42.2%, with severe misclassifications in 20%; combining DIN and LC1 improved accuracy to 80%. In Stage1, 56.3% of cases were managed conservatively, 24% with injection, and 20% with suture repair. LC1 cases were treated surgically more often (66.7%) than DIN (55.2%). Pulmonary complications and intraoperative anatomy strongly predicted surgery (odds ratios: LC1 306.8; pulmonary complications 39.2), with interpersonal variation as the third strongest factor. Injections were favored for DIN and suture repair for LC1. Conclusion: Interpersonal variability is not only considerable in diagnosing interarytenoid anatomy but also a strong determinant of surgical decision-making. Management reflects lesion severity, patient-specific factors, and surgeon habits,with injection often serving as both diagnostic and therapeutic in gray-zone cases. Recognizing anatomical and interpersonal variability is essential to standardize LC1 and DIN management. Incorporating patient-specific factors and awareness of surgical habits can guide appropriate intervention, reduce unnecessary procedures, and optimize outcomes.