I believe that if you do well on the tests your scores will be good. Some people are delusional thinking that without any preparation or any serious and smart (keyword) commitment they'll be able to get the scores they want. Everybody needs to prepare on their own special way, some people may study for 1 week and get the score they want, come people take the exam 8 times and fail. If you don't have exam taking skills, that will also weight against you. It's a combination of a lot of things.
Also, I never understood why people say give an exam, or even write an exam. I supposed it was some sort of British English or an incorrect translation. I've always said take an exam.
Well I am not that grammatically perfect to distinguish between give, take or write a test (studied in native language till grade 10) so the English I learned was starting class 12th and graduation and then at work (interesting note: The Poem 'Mary had a little lamb' was taught to us in grade 7 )
Anyways, I appeared for my IELTS exam after preparing for one month. I prepared despite the knowledge that I have decent command in English and I scored Listening-8.5; Speaking-8; Reading-9; Writing-8. Preparation is the key. To compare, I scored Listening-7.5; Speaking-8; Reading-7; Writing-7 when I gave IELTS with minimal preparation back in October.
All the other talks of exam being rigged and biased against immigration etc conspiracy theories are there to distract your mind from putting the necessary work required to excel. I'd never pay any attention to it and rather prepare.