I'm with you on the regular stocks buy and hold theory.  Too much can influence all the varieties of that world.  Bitcoin exchanges, however, offer a pretty low fee and sometimes wild fluctuations throughout the day.  I try a little of the limit order floating out there while I'm away for several hours, but I also like to jump in the middle of it with a little 5-8 BTC trade to keep it exciting.  I always figure the .65% hit before determining the price whether sell or but.  put it in for each transaction, now we're talking a 1.3% difference minimum before you even come out on top.  So it really needs to be bouncing to get anywhere with it.