Originally Posted by rm -rf

Are you riding at night, at sunrise or sunset, or during the day?

I have the Hotshot pro 150. I ride during the day, and sometimes just past sunset.
I use the single flash mode, at 2 flashes per second. The flashes are extremely bright, and very short, so the battery lasts a long time. Probably 15 hours or so, but I charge it more often.

Yesterday, part of our group was a quarter mile up the road, in bright noontime sunlight, with some tree shadows on parts of the road. Most of the riders have Hotshots or equivalent. As I crested a short hill, the blinking immediately caught my eye, even though the riders weren't close enough to otherwise identify as cyclists. It's very effective.

One rider has the Hypershot 350, with a seatstay mounting, and it's pointed upward maybe 10 degrees. I can't ride behind him, from about 8 feet out to 20 feet or so, since the brightest part of the beam is dazzling, even with dark sunglasses.

Even my 150 is too bright for night group rides. I switch it to steady beam, which can be dimmed down, unlike the flash modes.
Solo at night I use the ramped brightness mode, kind of a "waa - waa" effect. I think it's less annoying to cars than sharp flashes, and it's quite distinctive, good.