I know brutha, this is an arguement that's been debated for years.. I believe it does work to a point but lots of variables in involved.. First, its just not one of those "supp's" that you will definetly feel and/or see working, like gear or even a stim or NO booster. Second, as stated above, if you already consume alot of good food sources and shakes that already contain alot of glutamine, you really don't need to supplement with it. Third, timing can be big part of it. I've read numerous articles that stated the best time to take Glutamine is at bed time. Its widely believed that Glutamine will help illicit a greater release of natural GH. If you do take it twice daily, you would run it post workout and then at bedtime.
I've found it works best for me when cutting and doing lots of intense strength & conditioning along w/training. On a sparse cutting diet you might not be getting enough glutamine so I use the pure powder and I use around 5-10gms post workout and usually 10gms at bedtime. I do feel like I get better recovery when doing that.