Why you keep landing on 6.5
Examiners look at four areas: answering the question, how paragraphs move, word choice and grammar. When the score stalls, one of them is usually holding it back.
At this level your essays usually answer the question and read clearly, but one area still goes up and down. Find out which one.
In short: find the one problem that costs you most, and fix only that in your next essay.
Grammar, word choice and linking all got comments; pick one to fix first in the next essay.
The point fits the question; the reason needs one more step: why it holds and for whom.
You try longer sentences, linking words and harder words; accuracy still varies.
Examiners look at four areas: answering the question, how paragraphs move, word choice and grammar. When the score stalls, one of them is usually holding it back.
If you only note the score, the next essay repeats the old problem. Add one line: thin reasons, a shifting position, stiff linking, or many sentence errors.
Stay with this essay. Turn the problem into one small task: rewrite one paragraph of reasons, re-pick the overview points for Task 1, fix one link, or correct one set of sentences.
It helps. A faster route is to find the area that costs you most and fix only that in the next essay.
Look at feedback on your last two or three essays. Start with the problem that keeps coming back, and circle the sentences that show it.
These pages explain the Banfen Writing diagnostic and blocker-repair method, Task 1 overview, Task 2 development, and common score blockers.
If you keep scoring around 6.0-6.5, finding the area that costs most helps more than one more essay.