Everybody in this thread - "Math math math math math, I'm smart, math math math, you're wrong, math math"
The only answer that matters:
Whenever you have RNG, people "feel" like they come out on the wrong side of the equation. People being mad at your game all the time = bad. Implement a system where you have a specific # of attempts to achieve a schematic. You have to RE 5 greens to get a blue, and 10 blues to get a purple. I'll gladly trade the "joy" of getting a schem on my 3rd attempt, to rid myself of the frustration of not getting one by the 37th, and then we are still making the investment in creds/mats/time etc.
I don't isn't that the fun of it all seeing those big green letters saying you know it even after you spend 6 mill for one Schematic to me it was worth it ...