On Mon, 31 Oct 2016 19:08:08 +0000 (UTC), Algeria Horan wrote:

b. Heat makes things worse even faster
c. On/off cycles makes things worse even faster
d. Vibration makes things worse even faster

So, given they don't heat/vibrate/cycle the LEDS (other than the 4 hours per
day), you'll likely never get the advertised L70 lifetime in the real world.

But what do you get for a 70%-illumination lifetime in the real world?

I forgot to mention that none of what kills the LED over time discusses the
frail electronics, which also fail.

So, we need to know how long the "LED drivers" last too.

The life of the fixture is the shorter of the two failure modes:
a. Inherent cracks between crystals get exponentially worse over time
b. The drivers suddenly fail at any time

So, we still don't have any decent grasp on how long LED fixtures last, in
the real world.