This is a good free source introduction to O'Neil's use of price charts.
IBD_AmericaGreatestOpportunity1.pdf
The thing is, these charts are all pattern recognition. Patterns are fine, but you have to be able to to define the patterns precisely enough to code into a computer algorithm. That way you can apply some data science and prove whether a given pattern has a positive expectancy. Otherwise, one could waste a large amount of time and money on subjective analysis trying to collect such proof.