I use flash mode during pre-sunset hours and solid a bit after the sun goes down and it gets darker.
The flash makes it more noticable when there is already ambient light.
This morning (a few minutes before sun was rising, but already bright enough to see) I turned right and a flashing light caught my eye way down the road in the distance among all the brighter rear taillights of cars. I knew immediately there was a cyclist there and confirmed when I caught up to them. I am not sure if I would have noticed if their light had been solid.
Even so, I prefer the solid light after dark.
Al