Getting an 8.5 in the IELTS exam
Looking back at what the IELTS taught me.

I spent around a week studying for the IELTS exam. I ended up scoring an 8.5 overall (Listening 9.0, Reading 8.5, Writing 8.0, and Speaking 8.5). Not too shabby.
What I worked on
The only thing I really looked at was the writing format. I did one practice writing assessment a day for 7 days. As someone who has spent a decent chunk of their childhood in a majority English-speaking country, I wasn't too stressed about the listening, reading, or speaking. I will say that my experience in proofreading research manuscripts came in handy. It made it quite easy to read and interpret graphs.
What I took from the experience
More than anything, I learned that the IELTS rarely gauges an applicant's grasp of the English language. It measures how well they can follow a specified format. If you listen to enough mock IELTS tests, you can probably get a 9. That doesn't really mean squat for your actual skill. The only factor that your language proficiency affects is how long it takes you to get there.
Do I wish I studied more? No. Do I wish I studied less? No. Does it fill me with gratitude for the privilege of being taught English since childhood? Without a doubt.