For the short term even the 10-20% margin is quite high according to me. Just a small variation is enough to book the profit.
For that, traders have to test and experiment. They have to see if getting profits about that range is profitable for them in the long run.
There's really no exact moment when to sell but the right timing indeed.
If failed on the first test, try other tests until seeing the effective strategy that anyone can use in the long run.
It is important to know how will you adjust in times that the strategy is not working according to how you perceive the movement.
Many experienced traders work with how they see the current situation. They are good in
anticipating the movement and manage to earn out from the current movement. It's not
easy but the chance is possible, especially if you know how to work it the right way.