The short version of this post is:
DON’T MEMORISE ENGLISH IN ORDER TO LEARN SENTENCE PATTERNS.
IT DOESN’T WORK.
The simple reason is because it is obvious to the reader, especially the trained grader.
It will thus lose you marks simply because you did it.
It doesn’t work when learning English anyway, because the chances are, if you try to slip in a sentence pattern without really knowing what it means, then you are quite likely to make a mistake.
The easiest way that I spot when somebody is doing this when grading IELTS Writing is that, most of the time, the repetition of the sentence pattern does not fit the idea that the writer is trying to express. And then there is frequent incorrect grammar and sentencing anyway.
One of the most important ways to achieve good grades on your IELTS Writing is to express your own opinion about something and your own ability to describe something.
So you have to learn how to naturally express English, because if you repeat a pattern, then you are, by definition, not expressing yourself.
I could go on explaining why memorizing sentence patterns doesn’t work, and include testimony from people who tried, but another important IELTS skill is clarity. Being clear involves not repeating yourself, and efficient writing is better than using long words.