Well I agree that it's down to skill to practice them and get them right. But even the best drivers can't get all the manouevres right 100% of the time. With parrallel parking and 3 point turn, as long as you do the same thing every time, you can pretty much guarantee you'll get it right. With reversing round a corner and into a bay, however, it is largely dependant on where you start from, how tight the corner is, or how narrow the space is, etc. I practised for about 4 days solid before each of my 4 tests, and I could never get reverse round a corner or reverse into a bay right every time. Neither could my dad, who's been driving for 35 years. Therefore I came to the conclusion that, no matter how many times you've done them, there's still an element of luck as to whether you get them right or wrong on the day. Luckily I managed to get reverse round a corner right 2/3 times it came up, but still, I can't always get the car completely straight in the road when I do it, or as close to the kirb as some examiners want it.