The case is that the lower time interval the more volatile is the price, that's why even if you have somewhat more than 90% probability of profit per year, this probability will lower down to almost 50% if you decrease interval to 1 day. So if you spend too much time checking the price, charts, etc, it's like playing coinflip. Moreover when you see the price is going down, your mood gets worse more than up, when the price is rising (I talk about the case, when you go long position) - that's a human nature. The conclusion is that you better spend more time on doing other things, self-developing, reading books and analyzing different new strategies, rather than keep monitoring your trading positions.