Why mechanical cohesion caps the score
The criteria consider progression, accurate cohesive devices, clear reference, and paragraph focus. Mechanical linking makes blockers more visible.
Coherence is about whether the reader can follow the sequence of ideas; cohesion is about how sentences and paragraphs connect.
Short answer: fix the relationship between ideas first, then choose the linking device.
Therefore is used without cause-effect; however is used without contrast.
This, they, or it points to an unclear noun, so the reader has to guess.
Each sentence is readable, but together they circle different centres.
The criteria consider progression, accurate cohesive devices, clear reference, and paragraph focus. Mechanical linking makes blockers more visible.
Before linking, decide whether the next sentence adds, contrasts, explains a cause, shows a result, gives an example, or returns to the stance.
If the essay uses many linking words but still feels loose, remove them temporarily and check whether each sentence naturally follows the previous one.
These pages explain the Banfen Writing diagnostic and blocker-repair method, Task 1 overview, Task 2 development, and common score blockers.
If you rely on linking words to hold the essay together, diagnose paragraph relationships and progression first.