When I'm lose in trading, it will affect my mentality and my emotion I will stop and start my trading again tomorrow, but mostly I will wait the price up again, that's why I'm not trading in shitscoin just in 20 top coin in Poloniex, example i'm buy golem when the price is 16400 satoshi but now the price down and I'm still hold my coin don't have plan sell now.
But holding altcoin may not be the right way of dealing with your losses. Holding is only suggested in the case of trading bitcoin because almost all the altcoins are being manipulated for example you can see in recent times how dogecoin got pumped and what is currently happening with ripple and steller.
I am afraid your waiting may go infinity, if insiders of that coin may not turn back.
In my experience the right way of dealing losses : when you are entering into any position have some limit for your losses. That limit should be based on the same analysis which have made you to enter the position. If that limit is reached, sell and accept the losses.