The way (not) to study past exam papers

It has always been a popular practice to study past examination papers as a major way to prepare for examination. Not long ago, I sent out three past examination papers to students. They said they were important for their examination revision.

Subsequently, when I marked the examination papers from the students,  I found that many students just wrote down the figures and steps from past examination paper answers for examination questions with different figures. That is, no matter what has been asked in the examination papers, as long as the questions are very similar to the old questions in previous examination papers, they just wrote down the previous examination answers for the old exam. papers.

There could be many reasons why students did that, such as too much workload from another subject, or that the quality of teaching from the teacher (i.e. me) is poor. Nevertheless, this way to study past examination papers as examination preparation is highly problematic, and we are talking about university students from a decent university, not naughty primary school students from notorious primary schools. There are other learning attitude problems from the students, and I just do not have mood to discuss it...