THERE'S NO HOLY GRAIL IN TRADING

Spent the whole afternoon trying to create a system for very short term trades and I think I finally understand what they mean when they say there is no HOLY GRAIL in trading.  In a specified period of time, say one year, no indicator or system can be applied successfully or profitably to all stocks.  Individual stocks behave differently in the period of time and thus affect the profitably of a system.  So think carefully the next time someone shows you his indicator or system made a profitable trade on a certain date.  It may be profitable on that particular trade only.