So everybody knows to get a star you need to get 5 quality points = 15 skill points
What is annoying is that when you train you get results in % gained in specific skills and not 0.1 skill point or so
So you need to start calculating how many % is 0.1 and from my experience sometimes 2% = 0.1 and sometimes more.
I don't know if I'm wrong but I bet when you have more stars, it's slower to gain skill points and that's fine to me.

I wish their was a more direct approach to this. Where managers would know how many % they have to increase to get skill points.

I think to have 2 parameters of quality (% and quality points) makes it more confusing.