At night I run all steady up front, my big taillight (MagicShine) steady, my smaller one (Cygolite Hotshot) on flash. In the daytime no headlights, Cygolite off, MagicShine on flash.
Since my commute is in pitch black through farm fields, flashing headlight is not an option, though I suppose I could flash one of them. The rapid flash actually might be usable as a headlight at the same time but I think you'd probably have drivers throwing crowbars at you pretty quickly - it's an intensely irritating thing, to the point where I wonder who thinks it's actually useful.
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Work: the 8 hours that separates bike rides.