I think it may be more beneficial from a probabilistic point of view to sell when a stock begins to drop after hitting a maximum and buy when it begins to rise after hitting a minimum. The intuitive reason is because trends tend to exist (I suspect it’s because of the heteroskedasticity of the time series), and only once the extremum is passed can you tell whether the point was truly an extremum.

I have to think of the math behind this a bit more, although for formulating my own trading strategy, intuition will suffice.