Using 15 points provided the best balance, especially since this was more designed for one shot games. You characters should be fairly competent at what they do. If you put 5 into everything, you basically pass any roll 2/3 of the time. At 6 / 5 / 4, you have 83% / 66% / 50 % pass rates, giving you something you are really good at, good at, and not good at. You could even go 6 / 6 / 3 if you were really min/maxing and be great at 2 things and terrible at one. Within a D6 system the percentages swing in bigger numbers with each point in a skill, and 15 points ended up being the ideal breakdown for me.