Experiences of Cycle Training

Re: signalling. I point (often at the spot in the lane where I want to go if there is a car in that lane behind me). I guess I should be "flatting" it. What's the reason behind this? More noticeable? Less likely to be confused with someone just pointing at something?

That's it mark. Not only is 90 degree "flatting" more noticable as you suggest, it's also the agreed convention