I don’t think you’ll get a definitive answer based on use. Most people tend to bob up and down brightness settings according to need rather than sticking with one level. I find mine good for around three hours plus of varied riding in the Peak, but I always carry a back-up light regardless. There’s also a rough battery level indicator, so you have some idea of what’s going on and can knock back the light levels accordingly.
Take a back-up light and see what happens would be my advice.