I kind of agree that the theory test is pretty much common sense, other than road signs... but really, there are only a handful of those you have to learn because most of them are pretty self-explanatory. I think a lot of fails are down to over-thinking the questions actually... the obvious answer will be the right one

. And half of the questions are like "YOU SEE SOMEONE BLEEDING PROFUSELY!! What do you do? A) Call an ambulance and elevate bleeding limbs, B) Laugh and drive away, C) Set them on fire, they're a goner anywayz."
The hazard perception, I think people fail because they haven't been told the "trick" to scoring high on it, and think if they start clicking more than once it'll take points off. Multiple clicks doesn't remove points, only clicking over and over will fail you for a section. So, best thing to do is to click as soon as you see something you think MIGHT be a hazard, and then click again when that thing is DEFINITELY a hazard. You can even throw in a 3rd for luck if it becomes a super-obvious hazard.
I got almost full marks on the hazard perception, even after missing half of one segment because my mind had totally wandered off

. I was sat thinking about what to have for dinner

.