It depends!. The longest that I hold a coin is about 1 week, where I needed to wait for its price to go up again so I will not loose. If you want to do tradings then you must monitor the price of coins always so you will earn. You will buy coins when its price is low then sell it when it goes up. You just have to look for the correct timing so you can earn more.
The longest that you hold a coin is about 1 week. Are you serious about this?
I don't think it is easy to always buy into altcoins just before it goes upwards.
I will learn to hold coins longer in 2018
