a trading system is good because it could take away the emotional side of trading. a cool trader who is just following his trading system strictly without emotions is better and stress-free compared to a trader that have no system at all and just randomly trades at will.
It's a long term journey, you keep improving your strategy as the trend does not always happen all the time, the market is changing so as a trader
you should know how to change for improvement.
Most of time, it is your skillset and experience which helps you in making wise decisions and that too at tough times. You need to study a lot in order to make some handsome amount of profit by doing trading.