Depends on time of day.
IMO at night you should have some light steady. If you have a light that has a steady + pulse mode, that will work. However, I feel that you should also always be running two rear lights at night since you can have one fail and not know, and then you're in significantly elevated risk. So I run one in flash and one in steady.
Generally with regular lights I run a slow flash and a steady.
If I have the DS500 mounted, I run steady+triple pulse at night, high power triple pulse in daylight.
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Work: the 8 hours that separates bike rides.