Letter to the editor concerning 'Learning curve insights in unilateral biportal endoscopic (UBE) spinal procedures: proficiency cutoffs and the impact on efficiency and complications' by Jing Peng, et al. (Eur spine J [2025]: doi: 10.1007/s00586-024-08632-9). - Liu CZ; Pan H; Zhang W (European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2025)