The goal, really, is to show that you can write a essay in that time, and a 6/6/6 shows that just as well as an 8/8/8 does.
But you should aim as high as you can, so keep reading to find out what it really takes to get a perfect score on the SAT essay.
The SAT Essay is scored separately from the rest of the SAT now, thanks to the changes that went into effect in March 2016.
While the essay is now optional (you don't automatically have to take it every time you take the SAT), some colleges still require students to submit SAT essay scores with their applications.
You'll need to use precise language to show mastery of English writing.
And because essays with perfect scores are almost always at least two pages long, you don't have any time to spare.
You have to read the article and analyze the way the author builds her/his argument, pick out the most important components to the argument, find evidence to support your interpretation, and plan out your essay before you can even start writing.
A lot depends on how quickly you can come up with a thesis and relevant support for whatever the prompt happens to be—you might find some articles easier to read and analyze the argumentative structure of than others.
You know that you should state your thesis in the introduction.
All of this will get you a 5/8 as long as you develop your points enough.