Hard to generalize for all altcoins.

There are those you buy because they are hyped and you want to profit out of that hype. So you buy low and sell high (always with a stop loss in case the market makes a bad move) and then usually forget about it.

There are those you buy specifically to hodl for a longer period, but then still you ride the wave, that is you sell it at highs and buy back at lows. If it goes even higher you still buy back because that is a long period investment for you.

Hodling a coin meant sticking to a coin and never letting it go in 2017. Now it evolved, and it means keeping it in your bag, but increasing the amount when got the opportunity by selling and buying back.

Of course, if you realize the market is going really bad, there is always the option to sell it all to turn to btc or fiat.