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.