Don't think it's due to anything I've read on the forum, but I've stopped wearing a helmet.
Used to wear one religiously, but haven't picked any of mine up in months except to move them while looking for something else.
These days I just wear whatever ballcap I have handy.
Since all my morning commutes are now before any hint of daylight I may start back wearing a helmet as soon as I get a helmet light. Bar mounted lights don't always put the light where I want it. The helmet would just be something to mount another light on.