LEDs are actually slightly less efficient when you pulse the current through them. The voltage is somewhat higher and the light output per mA is slightly lower at higher currents.
You are better to control the current at a steady value. Boost or buck circuits with an inductor can do that very well.
60 Hz is far too low a frequency. It will flicker horribly. Depending on the duty cycle, 100 Hz flicker can be really distracting or just annoying. I've been able to detect that an LED was being switched at 5 kHz with the naked eye.
If you are using a switched mode current control, the switching frequency will need to be up at 10 kHz or more if you want the inductor to be small.