I can’t think of anything they left unexamined. Breadth (37 lamps) and depth (beam patterns, real world run times) are present. Basic theory (why have a headlamp) and advanced issues (why lumens is a deceptive measure) are both covered. They don’t hesitate to contradict industry claims, both on headlamp specs and on the general way in which lamps are measured (the accompanying “Why Headlamp Claims are Deceptive” is outstanding). In short, the article took a huge amount of time to put together, and is absolutely worth some of yours to read. Well done OGL.