A flashing helmet light in not very useful.

The single most important aspect of a head-mounted light is the ability to aim it and see objects or dangerous situations that are not directly in front of the bicycle. A focused "spot beam" is generally the best lighting strategy.

For many years I used "Coast" brand light that has an adjustable beam. I would leave it in spot mode - most of the time - and aim it at street signs or the edge of the road to detect animals or object from side streets.