Especially in a combustion chamber like the Alfa, where the actual flame travels in something that looks like a shell of a ball- the final flame distance is quite large, and it takes a little longer to burn than a flat chamber (relatively speaking). The TS initiates the flame in 2 places, which actually moves the ideal ignition point closer to TDC, since it will burn the whole thing a little quicker.
Heh.. All these descriptions make actual sense... rather than the
thing I read once in a car magazine: "The second spark is fired 180deg
after the power stroke, to burn excess fuel and reduce emissions" (??!!??)