Originally Posted by
Best Girl
If you read it "as is", basically it is saying:
Main system = 40 circuits
Sub system = 30 circuits each
There is however no context as to how many Sub systems each Main system has.
I suspect the math is actually 40 x 30 = 1200. In other words, a regular person can fire about 20 circuits, Tohsaka can fire at max 1200.
The math actually weirdly checks out with Heaven's Feel, with Rin usually at double digits for mana, but can fire 1000 at a time with an infinite supply.