I've come to the conclusion that I'm not experienced enough to inject consistently yet. Sometimes it works amazingly well, other times not.
Recently I had a "big date" and the shot just didn't work. It seemed to have a bit of an effect for 5-10 minutes, then it was over. Since I've read you can't inject twice on the same day, I left it at that, but the night was a major disappointment (I guess everybody here can relate

So my question is this: if the first shot simply doesn't work, can I try again?