Joules of light are like milligrams of Aspirin. You don't take the whole bottle of aspirin you take 2.
Overdosing can be surprisingly easy with a powerful LED Light Bed. Overdosing, while unlikely to create damage, will create less benefit than the proper use. What this means is staying inside a chamber for 15 minutes when the peak dose is 10 minutes is actually less effective than 10 minutes. Or coming in for 3 sessions a week might provide no additional benefit over 2 sessions a week.
Dr. Hamblin suggests we want irradiance to be under 100mw/cm2 on the skin and that we should be between 30 - 60 mw/cm2 for reds and near-infrared. ARRC LED is dose optimized at a verified intensity at 83.9. If the peak dose for performance is 30 Joules (per a recent study), then 83.9mw/cm2 would hit just over 30 Joules in 6 minutes.
Peaks for pain relief can be much higher than the peaks for performance which means a person could stay in the chamber longer (10 - 12 minutes) with the same intensity.