The teaching and learning of polymorphemic words is studied from the viewpoint of psychology on the basis of criticizing traditional methods of lexical learning.
At the very least, you need to understand that your IELTS writing score is made up of four different parts: task achievement, coherence and cohesion, lexical resource (which means vocabulary) and grammar.
And then for a level four response, you're allowed to have few lexical or grammatical errors; so again, a level four response has maybe a few grammar mistakes or word choice mistakes; it's not perfect.
For fluency and coherence, it's between 7 and 8; for grammatical range, it's a solid 8; for lexical resource, it's between an 8 and a 9; and for pronunciation, again, it's a solid eight.
So for lexical resource, you'll have to make sure that your essay is virtually error-free and that you used a wide range of vocabulary in a natural and formal way.
So the marking criteria for the IELTS speaking section are categorized as fluency and coherence, lexical resource, grammatical range and accuracy, and pronunciation.
Again, if you make an outline and we are well prepared for our essay, you can spend some time on your lexical resource without freaking out about these two points above.