yer there was another thread floating around about a guy who had his GS stuck at respectable, but it was over about 5-6 weeks. and the guys minutes were really variable. like, 30, 55, 60, 90, 45, etc.
Unfortunately GS is just one of those things, and a mystery to the users of this game still. Some players are easier to manage their GS, others... well... are like your guy.