On rare occasions, the market is clearly overpriced, as it was in 1987, before the great crash of that year. I knew that the market was overvalued for a year before thee crash, so stopped buying. Like a lot of people, I knew that the market was overvalued, but did not know when the correction would come, or how bad it would be.
So my market timing was only slight, but I avoided buying at a bad time. I sold nothing, rode the crash out, and my shares eventually went up again, as I knew they would. I have been watching the stock market since the lat sixties, and knew that there are rare occasions when the market is high, but the amateurs do not know that. The professionals sit on the sidelines, and the amateurs create their own crash.