Briefly, the raise magnitude has to do with the amplitude of the raised alert, and is different for different situations.
For example, if you raise a spike of X, then Sophie will tune to alert for X*n (n is a configurable factor) and higher, about 1.5 by default.
If you later raise a low-spike, it will not change anything, as the tuning was already for a higher number. So you can click Raise a bunch of times for a pattern without inadvertently raising it out of reach.
If you raise a higher one, then the tuning will adjust. As you provide feedback, Raise the higher value, remove the other alerts that may have occurred, and watch for the next one to come in. If it does, click Raise again, and it will only take a few times before you have the alert dialed in to where you want it.
This means fewer of this kind of alert, obviously. But it also means that other, potentially more interesting alerts can be surfaced. So go ahead and Raise your game with Sophie!