Background: Management of endometriosis should be based on the best available evidence. The pyramid of evidence reflects unbiased observations analysed with traditional statistics. Evidence-based medicine (EBM) is the clinical interpretation of these data by experts. Unfortunately, traditional statistical inference can refute but cannot confirm a hypothesis and clinical experience is considered a personal opinion. Objectives: A proof of concept to document clinical experience by considering each diagnosis and treatment as an experiment with an outcome, which is used to update subsequent management. Materials and Methods: Experience and knowledge-based questions were answered on a 0 to 10 visual analogue scale (VAS) by surgery-oriented clinicians with experience of > 50 surgeries for endometriosis. Results: The answers reflect the collective clinical experience of managing >10.000 women with endometriosis. Experience-based management was overall comparable as approved by >75% of answers rated ≥ 8/10 VAS. Knowledge-based management was more variable, reflecting debated issues and differences between experts and non-experts. Conclusions: The collective experience-based management of those with endometriosis is similar for surgery-oriented clinicians. Results do not conflict with EBM and are a Bayesian prior, to be confirmed, refuted or updated by further observations. What is new?: Collective experience-based management can be measured and is more than a personal opinion. This might extend EBM trial results to the entire population and add data difficult to obtain in RCTs, such as many aspects of surgery.