Not always. It depends on the situation each time. Let us say you are 100% sure that altcoins you are holding will never grow. Then sell them. The other situation is that when you believe in your alts’ growth. Why should you get rid of them then?
But this is a decision that should have been made long before you invested in these alts right? And if you are a day trader (which is what they thread is about),,, then it's not about holding but making decisions for the day on a strategy that is kept within the same day to keep your capital mobile about the whole market every day right? You always exit, at predicted stops.