Dr Tufton, head of biology at Beauchamp College, Leicester, said that for AS and A-level courses, students not only submit a piece of coursework, but a set of "second tries". These are used if the original piece is not up to scratch.
Teachers spend an hour per student per year marking the work and then sitting down with pupils, suggesting areas where they might want to improve it.
Marking demands can be huge: typically, staff spent three hours per day in the first week of the Easter holiday marking coursework.
Dr Tufton, an advanced skills teacher who has taught at the college for nine years, said schools were investing time in coursework, at the expense of more enriching learning, because of the pressures on them. "Every school in the country has worked out that time spent on coursework improves their overall exam results."
He accepted that many people supported it because it gave students a chance to demonstrate their skills outside the exam hall. But he said that pupils who do well in exams also excel at coursework.
It was also difficult to design different examples of practicals from year to year with the result that students with older brothers and sisters often benefited from help.
There were also internet websites offering downloadable coursework essays, making cheating easy. Dr Tufton said: "There are just too many problems with coursework as it stands. The idea of having students assessed across several subjects through one piece of work is one I would very much support."