Holding is good for top-in-the-future coins or if you are a dumb in trading. Trading is perfect is you have some-working strategy and some experience in that. Trading allows to achieve results much, much faster than hodling. Hodling is a passive thing that won't help you get to the moon. Honestly, hodling is the best strategy for most traders/investors.
Trading is good because in holding your coin you will not be aware of it that when the price of the coin will increase as no one know about the market change but in trading you can sell your coin at high price and you will keep check on Market all the time. So better to trade or apart from trading you can put some bit coins holder for long term.
That's also advisable but it depends on the trader itself, if the trader has no skills in trading then I think he should not force it. Holding alone is a good strategy already as long as you keep yourselves updated of what is happening in the crypto space, that way, you can make a decision to sell in a good timing, but of course that should be based on your set target.