It isn't so much the reflective during the day, as the hi-vis. I have a hi-vis (and reflective) vest for warm weather (including a second attached to my backpack, for when I ride with it), and a hi-vis wind shell for cooler weather. I'm considering a true jacket for cold weather (which would also be hi-vis).

I do think people are conditioned better to look for the screaming hi vis colors because of all the highway worker safety campaigns.