Depending on who you ask and who you believe, LEDs may lose half their brightness after 10,000 hours of use. Or 5,000 or 50,000, depending on who you ask.
So if you take 10,000 hours, divide by 24 hours per day, leave the LED on all the time...that's some 416 days before the LED is at half-brightness, which isn't a good thing. Leave it turned OFF during the daylight hours...and you obvisouly double the life, or more.
Then the only question is whether OGM, or anyone else, will quote you a number of hours and send someone out to climb your mast and replace the LED if it dims sooner than that.
FWIW, I've seen a number of Leviton brand white LED night lights (junk from China) go from "incredible" to "is that on?" in only 18 months of near continuous use.