the S-MAC station in halo two, Cairo, with cortana controlling it, was able to fire like once per minute. and Truth's fleet was also weakened by the sanghelli breaking away
thats a good point also in halo 2 the Sanghelli took on the loyal cove fleet... but now that i look back on it, its kind of sad that even with the Sanghelli braking away and taking on the rest of the fleet that the UNSC still couldn't hold there ground in space when truth hit them and the worst part is that the UNSC was still a full strength. THAT FUCKING SUCKS!!!!!!!!!