I remember from one of your other posts that you’ve already passed HSK 4.
I recommend focusing hard not just on HSK 6 study materials, but also on what you’ll need to communicate successfully in the industry you intend to enter.
There will always be specific language and expressions, and no testing system, even the rather extensive HSK system, prepares you for everything you need to know. I Tested HSK 4 in 2011. I’m probably HSK 5 now. I work at a Chinese auto parts manufacturer where the primary language is Chinese and a decent amount of the top level management speaks little English. Had I passed HSK 6 prior to starting here I’d have still faced many many challenges.
Best thing you can do is live the language. Get a tutor, study hard, but also strive to make Chinese friends who have no interest in learning English. Then hang out with them as much as you possibly can. Immerse yourself. Watch Chinese TV, read Chinese newspapers, listen to Chinese talk radio. Read. Write. Communicate. Listen. The only way to truly increase the rate of your improvement is to increase the amount of time you spend studying. That includes conversations with locals where you’re forced to use the vocabulary you’re learning.
I’m not studying HSK right now, but I plan to sit for the test before the end of the year to see where I stand. Should be interesting.