Just on another note. if you're painting 15mm it's a good idea to go for a larger contrast or you may end up with a muddy looking mini so if using the AK Triads I'd use them as they are for 15mm. For 28mm I would tone them down- starting with a base of mixing "A", then "A" and "B" mixed, then B as the third layer. Perhaps mix in a bit of C for the very highest points of highlight.
I used one of their British sets just like I have described and got very good results..... see below:
As I say, O personally would use a higher contrast if I was going to paint the same in 15mm.