The way the grand jury works is a combination of massive inefficiency in some places and meticulous attention to detail in others. Of course, I could only imagine the inertia one would need to overcome if they tried to reengineer and optimize it. This is probably why no one tried.
It is interesting how so much care is given to making it hard to indict someone.
Also, it is interesting to spend the time with a completely randomized slice of Brooklyn population – much more so than a regular trial jury would be.