Light sources can be pulsed (with pauses between light emissions) or unpulsed (with constant output over time).
The human visual system perceives a light source shortly after it has been switched off, this is known as persistence of vision.
I conclude that a pulsed light source might seem brighter than it actually is on average.
This leads me to the following question:
What is the perceived brightness of a pulsed light source (let's say, pulse frequency of 100 kHz, duty cycle of 1/1000), compared to the perceived brightness of an unpulsed light source?