Honestly, its really hit or miss. I have a 00 brush where I tried to use it for edge highlights but I am now using a 1 brush and having more luck.
The key with the 1 brush is to thin my paint a tad and dab a little on a piece of paper first. If it works out, I can pretty much do a 45 degree angle with my brush to the edge and apply without pooling any of the paint and blotching it up.
If I am lucky with that same technique, I can also apply it directly to the model like I am just painting with basic strokes.
Some paints I have had better luck with then others in the Citadel line. It really is patience and trying to lightly hit the model and continue with the same strokes over top of each other building up the color.
I really need to practice personally more on it.
The last thing I guess to say is at times, I also have good luck when I have more paint on the brush. My mind believes if I just keep a small amount on just the tip, that is enough, but more often then not, there isn't enough life on the tip before it just dries up before being applied. Having more paint on the brush allows it to flow off easier, consistently and for a longer time.
I have a funny feeling I wash my brush too often after every application to the model and by doing that, I keep artificially loading water onto the brush, which I then add back into the paint on my wet palette.
Painting is so complex and complicated. But like most people will say, in order to become good/great at something you have to put in the hours (what was it, 10K hours?). I think am around 100hrs. Many many many more to go.
EDIT: The models look really good just with the naked eye on them. When taking such close up shots and using SHARPED filter no Photoshop, it really makes the models look bad. But that's what you get when you take a microscope to it
Regardless, listening to some professional model painters and hearing the best take away that you "can never paint the perfect model", allows me to see my errors or weaknesses and move onto the next model with that knowledge and hopefully I correct it.