As far as you make realistic targets, I think it will be a healthy way for taking profits. You must already analyze everything on your altcoins before you make your targets for taking profits, I'm sure you know how realistic your targets are. Just don't trust totally the people who say the altcoins can increase hundreds percentages, it is because not every altcoin can experience it. It is mostly for new altcoins that rely on the hype, but they are very risky altcoins for investment. They can increase drastically, but they can drop significantly as well. I suggest you to focus on top altcoins which have strong fundamentals.