This is a dumb question from someone who just buys and holds, but if you have a strategy, why can't this be instantiated in code and then it just trades for you so you can spend your time doing something else?
When one starts thinking about how to look at all those factors and when one starts thinking about how to measure those factors (what is volatility? What high or low? Compared to what baseline? Does the baseline move?) it becomes clear that the problem is a bit more complicated to measure and implement in code than it is to train oneself and trade discretionary.
With very fast execution (think server collocation on the exchange and direct fiber network access to the exchange server) the possibility of market making opens, I think of the things that Jane Street does, and look how crazy profitable they are. But very few people have access to that.