Official reports into this summer's exams also show pupils sitting the subject at Standard Grade are being given template essays, with very similar answers from candidates in the same schools.
The findings by the Scottish Qualifications Authority (SQA) – the national exam body – raise concerns over the practice of teachers encouraging pupils to regurgitate off-the-peg answers.
The reports also raise wider questions about the effectiveness of exams in assessing the range of pupils' capabilities.
The concerns were echoed by parents, who said the practice would "stunt creativity", but teachers' leaders said it was inevitable given the pressure on school staff to ensure pupils passed exams.
The SQA report on Higher English said there was a "disappointing sameness" about many of the essays marked.
"There was more evidence than in recent years of candidates coming to the exam with prepared answers, often on questions from recent exam papers, and attempting to adapt these to fit the questions asked," it said.
"It was disappointing to see, once again, that in some centres whole classes had been set identical tasks. This is very unlikely to generate work of quality.
"While class exercises are a worthwhile tactic in the teaching and learning process for writing, candidates should be allowed the freedom to choose the nature of their final submissions."
The SQA report said the overuse of one text by pupils sitting a poetry question "leads to the suspicion that significant numbers of candidates are coming to the exam with just one poem on which they are determined to answer come what may".
On Standard Grade English, the SQA warned of the practice of so-called "scaffolding" – where pupils are given a template to answer essay questions.
"Some markers commented on over-reliance on scaffolding, which restricted candidates from showing flair in their analysis and from displaying personal response fully," the report said.
"Overly prescriptive planning can lead to several very similar pieces being submitted by a centre, as well as limiting the opportunities for more able candidates to demonstrate their individual flair and genuine engagement."
Eileen Prior, executive director of the Scottish Parent Teacher Council, said the practices highlighted by the reports could hinder the development of pupils.
"It's very disappointing because we know this kind of learning stunts creativity and reduces opportunities for our young people in the long run," she said.
"Schools are under pressure to produce good results, not least from parents, but these good results need to be based on sound educational foundations."
A spokesman for the SQA said experienced markers were well-versed in spotting tactics such as scaffolding and fitting pre-prepared answers to unsuitable questions.
"These tactics do not benefit candidates and do them a dis-service, because they can stifle creativity, introduce irrelevance and thus depress grades, especially in subjects like English," he said.
Alan McKenzie, acting general secretary of the Scottish Secondary Teachers' Association, said "teaching to the test" was unavoidable given the enormous pressure on school staff to get pupils through exams.