I'm not intending to lecture and I apologize if it comes off that way. I said the the igniters used for fireworks were different because MJG has different ones for fireworks than for rocket. I am an educator and my "voice" might sound like a lecture, which text communication on the internet seems to amplify. I'm also a life-long student, and if I need to learn something, then I'll be happy to learn from those more experienced.
I'm not sure I agree here. For example, let's say you have three igniters in series and they all have minor differences between them. Because of these differences, the second of the three igniters fires before the other two. The electrical connection to the others igniters is cut, preventing them from firing. At best you get the first two to fire. Your rocket launches on two of three motors, which isn't great. Or it could fire on just one, which would be even worse. Actually, since the electrical connection is completely cut from all igniters in series at that point, it seems highly likely that *only* the one would fire.
Is there something I'm missing here where less than all the motors igniting is a good thing?