My experience is as you describe - you HEAR many grouse flushes, but get few shots. It's fun though! If I wanted meat for supper, I'd leave my lab at home and poke around on my own. But I still have fun when I take her. What I do is I try to stay on trails and old roadbeds and have her go in loops into the cover on either side. When I see her get red-hot I try to keep along side her, especially trying to find places where the tree cover is lower or thinner. I also have some grouse hotspots that are very concentrated - lone old apples trees, or thick patches of hawthorn. Approaching those I slip a leash on her and then release her when we get there. But yeah, if I'm following her through the woods, especially here in Nova Scotia where the woods tend to be generally quite thick, I don't get shots at many.
-Dave