In that case, can't they just create their own multiple steps? Or they have no idea that it's possible to have more than one step?
It's not just the number of steps, it's also that her method is very simple, so easy to visualize and incorporate for other people.
As the lesson from the teachers show, there is no real teaching of compression in the Academy, so each person try to compress based on their own ideas. Most only use a very basic idea, like Rauffen just pushing back the mana (which is pretty much only the step 1 of Rozemyne's method)
If someone manage to create a great method, he's more likely to keep it hidden as a heirloom technique taught only to his descendants, in order to get more influence down the line.
It is pretty much confirmed that the best technique ever discovered before Myne (spoiler for P5V7 LN)
is similar in efficiency as Rozemyne's second step. So her 3rd step is incredibly strong, and her 4th step is just pure insanity in terms of efficiency compared to what even the best nobles have access to.