After 30 years of driving a car I went back to 2 wheels, did my CBT & DAS, the instruction was perfect - the trainee struggled. CBT was a bit of an eye opener & made me realise how over relaxed my driving was (I drive about 35K miles annually),no problem with braking angears but even on the 125cc the U turn was going to be my nemisis - but got through the day thoroughly enjoying every minute.
My DAS was booked for 4 weeks later, I asked for it to be 4 days instead of the advised 3 days so had my first day as a 1 to 1 on a 125cc, then for the next 3 days on a 500cc. First day on the 500's was a few hours on the training ground to learn control on the bigger and heavier bike, the U turn again made me sweat a bit, and we learnt to have faith in the front brake (old pedal cycle memories). When we took to the road all of the reasons that brought me back to biking were realised and I knew this was the right decision.
Over the next 3 days every hour was a pleasure, but the U turns were practiced in the most narrow of roads and were a 50% ratio of OK/poor - but gradually came together (look at where you are going, nothing else)but they seemed pointless. Also my training center/base was 14 miles from the test center so a daily return of 70mph was required, I agree with the other posting it seemed a bit dangerous on a naked bike with all of the wind etc, but this is a daily element all riders just get on with.
Test time came, I was nervous, the examiner was so calm he could have been my dentist so I was very much at ease. And so to my nemisis - The U turn was on a much wider road yippee, but due to extreme concentration I stupidly left my sidestand down after walking the bike to the other side of the road, a fail regretably & I felt a right lemon. 2 weeks on, the retest, all went like a dream and passed.
Since then 70mph on a road is fairly calm, and due to traffic/obstructions/wrong turns I have actually had to do 3 U turns (this time no bother). Despite a mistake, this was the best thing I've ever spent money on! & even if things seem pointless, you may need to do them at some time.