I touched on this last time, but I'll go a bit more in-depth here. Reflective material is not helpful at night. I realize this might seem counterintuitive, but it's true. Unless I'm turning the car and pointing the lights at your house or mailbox or wherever you've put these reflective numbers, all I get are flashes of the numbers as my lights brush up against them and say, "I do beg your pardon" before moving on.
Heck, sometimes I can point my flashlight directly at them and still can't make them out... the angle is off, or something just isn't right. The force is not with them. Much more helpful than reflective material is a good contrast between the numbers and whatever is behind the numbers. That helps them stand out in low light.
And a freebie with this tip: One easy test to see if you have easy-to-read numbers--and thus an easy-to-find home--is to ask several people who don't know where you live to find your home by consulting a map before leaving to get there--no checking the map once they've left for your place, and make sure it's a night-time trip. And pick friends who aren't too nice to point out ain't no way nobody can find your house because they can't read your house numbers (or your neighbors').