Cooking squid. How come recipes say to cook 15 minutes (in tomato sauce) and others say 1 1/5 hrs?

I know to either cook super fast, or stew slowly to get squid tender, but how long is right, or too long? Some recipes I've read, for squid in tomato sauce, say to cook 15 minutes to get tender, others say cook for 50 minutes to an hour and a half. What the heck? Can't it be overcooked? I can't afford to screw this up, I only have so much squid to work with, so I'd like to get it right the first time. Any help?