Answer
There is no recent information available about the effects of mandatory retaking of a (theory) test. Up until the seventies, retaking of a (theory) test was mandatory in Norway; when this principle was abolished, negative effects on crash risk did not occur [8]. Since the initial theory and practical driving tests do not show a marked relation to crash risk (see the question What is the road safety effect of the driving test?), we do not expect retaking a (theory) test will have much effect.