I switched to flashing mode on the road the day that I got pulled out on. I was on a straight road, the other driver had a stop sign on a T intersection. It was dawn, enough light to see without the light but I had it on anyway (550 lumen or so Magicshine), I was wearing an ANSI reflective vest, and there is a solid quarter mile of visibility there. The car just pulled up, rolled the stop sign at about 10 MPH and hit me. I saw him coming and swerved enough to just run tangent to him while pushing off his front bumper around the corner.

It turned out to be a guy I know from work. He was really shaken up and said "I swear I didn't even see you."

That day I decided that I would just bolt on more lights and make them more irritating until drivers saw me. I'll set every other bush by the side of the road on fire as the light turns on and off, if that's what it takes to get drivers to not kill me.

OTOH, I'm halfway convinced that there's absolutely nothing within the realm of reason that will absolutely guarantee that they see you. I think some drivers would "not see you" if you were riding a full-grown bull elephant painted neon green with six illuminated Christmas trees tied to it.

But IMO you have to at least try.

If I was on a bike path though, I'd definitely point the light down if I thought I needed it on flash. But since there's no such thing as a bike path anywhere within 100 miles of here, it's not something that comes up.

Generally I run on solid/low in the daytime but there are some areas where pullouts are a definite hazard and then I switch to flash.