I've used it non-stop for up to 8 months before, and have recently been using it non-stop for about 2 months.
I never noticed any decrease in strength when I stopped after the 8 months (I stopped for 3 months after), but maybe I would have gotten stronger had I stayed on it. I don't really know.
I did notice a slight weight gain in the first 2 weeks of going back on it, and felt stronger within the first week.
I'm thinking that, for me, it seems like the strength/size benefits are only noticeable when getting on it again, but the opposite has not been as noticeable when not using it.
I plan on using it steadily, so the times that I've gone without it were mainly because I forget to take it, or I run out and don't have enough money at the time to buy more.
I was using approximately 5 grams, or one heaping teaspoon, each day.