Teenagers in England and Wales spend more time on exams than pupils in any other European country, according to new research.
Politicians are criticised for trying to maximise results at GCSE and for forcing children to spend their time on revision rather than on gaining new knowledge.
Across the Channel, teacher assessment is relied on much more than these "high-stakes exams" which put teenagers under pressure at an early age, said Dr Anne West, director of the London School of Economics Centre for Educational Research.
The LSE report, Secondary education across Europe, compares the curricula, assessment and exam systems in non-vocational schools across the continent.
Its authors, Dr West, Ann Edge and Eleanor Stokes, found that the UK and Ireland test teenagers in more subjects than other European countries - which tend to test the language of instruction and maths, plus, sometimes, a modern language, says the report.
Dr West said: "Hardly any countries have such high-stake exams equivalent to GCSEs at the end of compulsory education.
"A lot of political energy is put into maximising the results at this level. So much time is taken up preparing for exams, often just reinforcing what has already been learned rather than gaining more knowledge. Is it right that the policy focus is on what happens at the end of your 16th year, rather than your 18th year? GCSEs put a lot of pressure on at an early age."
Only Dutch and German vocational schools run similar high-stake exams at this age - usually because they have a direct link to the job market, says the report.
Dr West said: "It is likely that once children here have obtained five GCSEs at grades A*-C they feel equipped to join the jobs market. It may be better to have such qualifications at a later age - this would be a better incentive to stay on than say the graduation certificate proposed by the Government."
Only in the Nordic and English-speaking countries do pupils automatically pass on to the next year at school - in the others exams and teacher assessment.
Children in England, Wales and Northern Ireland spend the least time studying a modern language, but the most on science.
This week delegates at the Professional Association of Teachers' conference were told that exams were akin to child abuse. Pupils were shut away from the "glorious fresh air", regurgitating facts.
Secondary education across Europe: curricula and school examination systems, LSE, Houghton St, London WC2 2AE, pound;10