While at another Vassar concert, I noticed a manufacturing date stamp on one of the LED exit signs in Skinner Hall:

I like the “Replacement lamp not applicable” line. I wonder how recently they’ve tested the battery for the projected 90 minutes of backup time…
These old LEDs show the expected brightness variations:

So, now you know what your discrete LEDs will look like after two decades of continuous use. That’s if anybody (else) still uses discrete LEDs, of course.