Well, my feeling is that you need to believe in the company at the time you invest, because that's what provides the fundamental background for the shareprice appreciation you're expecting. Otherwise you're just hoping a greater fool will come along and take your shares off your hands before everybody figures the game out and dumps.
But for me, as soon as I buy, the safest play is to forget everything I know about the company and just go on price. When I do that, it generally works out. I've had numerous cases where I didn't make as much money as I could have by sticking with a company, but also never taken a major loss in those situations. The problem with hanging in there is that it amounts to refusing to admit that you might have been wrong in your original idea, and then, to support the 'hanging on', you start to desperately look for reasons why things are going against you, and waiting and hoping for the turn-around. And that's when you get in the situation (like I'm in now) where by the time you accept the fact that you must have been wrong all along, you've already paid the full price,in terms of lost time, opportunity and capital.