Though it’s of utmost importance to know the cohesive devices, its equally important that students don’t learn a long list of cohesive devices, and if inspired to learn then ensure that meaning of each word and its usage is completely and clearly understood. If you use the wrong word, it confuses the reader, and this lowers your mark for both coherence and grammar. It is better to use no word than use a word incorrectly. Learn just the words you need and learn them 100%. Finally, don’t try to use very complicated words and expressions if you are not already comfortable with the simple terms. Being able to use ‘and‘or ‘but‘ effectively is much better than trying to use more complicated words incorrectly.
The overuse of certain cohesive devices by the students definitely causes redundancy in their writing and renders their written texts difficult to decipher. The students might be encouraged by their teachers of writing and discourse to use as many cohesive devices as possible to create cohesive whole texts. This, in turn, will certainly result in less redundancy and incomprehension.
Another common mistake is the misuse of cohesive devices by picking really informal ones or really old and unusual ones. One of the most common mistakes is saying “to recapitulate.” This is a term that almost no native speaker would use nowadays. You can see here on Google that it is no longer a commonly used term and unfortunately, many IELTS candidates use this as they are passed on with a wrong information that it is a special word to dazzle the examiner.