As mentioned several times earlier, using unfiltered LED light my pre-flashed tests failed after only a few minutes. But using a single layer of Rubylith I was able to completely eliminate the visually detectable blue and green spikes from my LEDs, then successfully test them with pre-flashed Ilford MGIV FB and RC as safe out to at least 60 minutes. I too gave up at that point.
They are not as bright as you describe. But I use six of them mounted in-line on a DIY fixture held magnetically on the top of my suspended Thomas Duplex and bounced off the above white ceiling tiles. This gives an excellent spread of soft red that does allow fine easel focusing of projected images, while allowing easy visibility of everything else in the darkroom.
And best of all, my whites stay brilliantly white. Even when using Slavich papers.
This is a valuable thread.