Times of knights searching for Holy Grail are long gone, but as for finding consistently profitable style of trading, that took about 3 years.
The lucky and blessed ones are the ones who blow up their trading account and never find it (in stock trading I mean).
The holy grail is consistently profitable trading. No one with IQ over 50 is actually looking for a system with 100% wins or thinks that's "holy grail". I would also say that holy grail is able to remain profitable even as markets change from year to year.