Long term is not preferred in the case of smaller altcoins. 3-4 years back, I had invested heavily in altcoins. I had a large number of different coins, including Bitsend, Byteball, Litecoin, Denarius and Namecoin. Apart from a few such as Litecoin and Ethereum, most of them have lost at least 95% of their value during the last 1.5 years. Some have lost 99% of the value and are no longer traded in the exchanges. The trick is to convert them to more stable assets (such as fiat cash and Bitcoin), when you are having a chance. Once the prices crash and the coin is no longer actively traded, you may not be able to encash them. Another thing that can be planned is partial profit booking at fixed intervals.