Well, it all hinges on each individual. But, most think that it has something to do with how well it shuts down your natural test. Soooo, a low dose of long acting test like cyp or enanth (I am talking 100mg-250mg/week) is enough to keep these emotional rollercoasters at bay.
I have been on fina for ~4 weeks and have not had one time where I lost my temper. I highly recommend fina, it is the best stuff I have ever taken. Just take it with test, that is all.