Honestly, I did not quite understand what you meant by art. And why, in your opinion, this art approach contradicts strategy in trading? I would say that developing strategy only benefits your way of trading, because you define some standpoints for yourself which help you navigate through the market. And following strategy doesn't obligatory mean that you would have to stare at the screen all the time. It really depends on your trading style and your self control abilities.
Art can be interpreted as a way to achieve success in investment and art can also be related to expertise, skills or what is often referred to as strategy in investment. Art is not much different from strategy, only people don't mention art in the investment process because people are more familiar with the term strategy. I'm not saying that looking at the screen all the time is important, but in particular traders face the screen more often as a way to see the trading process they are doing.
Without a strategy, no results can be obtained in trading because trading has much greater difficulties compared to investing. In trading terms, strategy is actually needed because without understanding patterns we will suffer losses when trading, that's why trading is much more difficult than investing.