Take profits near the upper channel line. If the market is strong, you can wait for the channel line to be hit. If it's weak, grab your first profit while it's still there. What if a strong swing overshoots the channel line? An experienced trader may shift his tactics and hold a little longer, perhaps until the day when the market fails to make a new high. A beginning trader is better advised to take profits after the channel line has been hit as it's important to learn to take profits in accordance with one's trading plan.
A scalper intends to take as many small profits as possible, without letting them evaporate. This is the opposite of the "let your profits run" mindset, which attempts to optimize positive trading results by increasing the size of winning trades while letting others reverse. Scalping achieves results by increasing the number of winners and sacrificing the size of the wins. It's not uncommon for a trader with a longer time frame to achieve positive results by winning only half or even less of his or her trades – it's just that the wins are much bigger than the losses. A successful scalper, however, will have a much higher ratio of winning trades versus losing ones, while keeping profits roughly equal or slightly bigger than losses.