Market timing is simply the act of selling a portion of your stock market positions to a risk-free interest bearing account when odds favor a significant stock market decline. There are very few advisors that do not use some degree of market timing. Individuals use timing. Most just don't realize it.
Every investment has to be bought at some point and sold at some point.
But they can't risk under performing their competitors by being only partially invested. Timing has some huge advantages. It's easier to accept small losses. Taking periodic small losses will not cause you to give up on the stock market. With timing, much of the time you are invested in risk-free cash .