If there were actually a point, a real defined point for taking profit, this would have been about that point where the change of trend would be greatly observed and about that point you'll find a hot spot for activities once the signal is given in the chart pattern.
Fortunately, there isn't anything such as these so, its always up to you to have a target and know when it is just about right to be contented with what you've gotten from an altcoin trade. Greed is always going to kick in once you tend to have reasons to make the most profit. It chocks!
The problem is that for most coins there is no point like that, in the case of bitcoin despite its volatility the price moves slow enough for you to find one of those points, to find a point in which the trend changes and allows you to sell for profits with relatively ease, but for most altcoins this is not true, they move so quickly that unless you're watching the market as that turning point happens then you're not going to be able to sell fast enough in order to keep whatever profit that you had from holding your coins, which is yet one more reason why it is so difficult to become profitable while trading those coins.
You need to have full knowledge in order to take this advantages.
Your skills in monitoring the movement will guide you to find certain point to sell your assets, in-case that you wanted to continue the
chase, you can buy low and sell high. It's always depends from how you percepts and how high your trust with certain assets, not all
can provide you the benefits that you are aiming but as long as you are updated from how things are working behind, you'll always find the position that might gives you some edge.