I'm not talking about Graham value plays for selling 1/2 on doubles but high risk junior energy plays like Storm Cat, AOGI, TPE, etc. As you pointed out how can one determine a true value of Storm Cat at any point in time? You can't.
I have about seven of these now. It only makes sense to follow this program. Also at times you can later reload position should it come back down. If one owns a "free" position in a high risk situation you can be very relaxed about price flucuations. In fact, I find myself cheering for a decline so I can reload.