I think with the old CBT rules 2 years on 1 year off was a better incentive to get further training and pass the full test, now people retake test after test without getting further knowledge, I thought I was a decent rider because I have had years of experience on 125's but after putting in for my test and watching a few mod2 videos it has opened my eyes that I could do so much better. There is so much to it that CBT does not teach, Or maybe I just had bad instructors but I have been to a few in Kent and Essex. I knew of people who ride really badly because they don't know any different, when they retake their CBT they ride for the test, not for themselves and then back to their old ways just because they got their bit of paper. Id say the theory test should be mandatory if you wish to take the CBT, at least some of the highway code might stick unlike CBT's I have been to the instructor just tells you on the day and most of it is forgotten by the time the candidate gets on the road. maybe even limit CBT to 50cc and make the a1 licence mandatory if you want to ride a 125.