Mail from AD
If LED flashes at 5-10 K Hz at even 50% Duty Cycle. It may save some power and improve life. So it is just an idea, it may not solve the problem. The idea was to improve battery life and give uniform light for annunciators. It may not be good for flashlights.
Light-emitting diode - Wiki
LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching.
The LED Museum
The LED (and Laser) Museum. A site devoted to testing & reviews of LEDs & LED flashlights in all common chemistries.
LEDs and OLEDs
Small lights with big potential: light emitting diodes & organic light emitting diodes.
Light Sources in Electronics
Light can be produced and/or controlled electronically in a number of ways. In light emitting diodes (LEDs), light is produced by a solid state process called electroluminescence.