With HID's I always ran at 100% since the spectrum is designed for 100% and I just raised and lowered the light to raise or lower the intensity, LED's claim they dont work that way so I did the same thing with them  last grow except I ran at 80% and worked well. When they got close to the end of flower I cranked them to 100% and added 2 hours of light to schedule to boost the DLI