I've gotta getta start much earlier than usual today, since I need to get home in time to shower and drive (!) downtown to dinner and theater. The curtain time is 19:30; the will-call desk is probably open at 18:00 or 18:30; the closest restau doesn't take reservs. So I hope to be home by 17:30, leave work by 16:30, start work by 08:00, and leave here by 07:15. If there is enough daylight by then. That's really my gating factor.
That gating factor, enough daylight to be seen by motorists, is a safety factor. Though I may be able to see well enough even at 7:00, it does me no service if a driver fails to see me and runs me down through both inattention and dim lighting.
Some fellow cyclists might refer to the superb illumination now available with LED lamps, and I acknowledge that they greatly improve the odds of being seen. But for me, it's a matter of trust and a knowledge that today's drivers are multiply distracted. Often too distracted to notice well enough that wobbly, weird light on the road.
Now at work, with benefit of my minivan, I feel more comfortable with the timing of the evening's activities. I effectively have given myself another hour to work, eat, attend, and arrive alive.
On the subject of illumination and being noticed, I found this product video from MonkeyLectric that is both fun to watch and consider buying.
But for me, the $60 price tag might be okay if the lamps were easily ported from one bike to another, and if the lamps were actually visible from behind and head-on. Unfortunately, the lamp assembly is attached to the spokes with cable ties, and the light show is visible only from the side.