While the Design stage was undoubtedly the most complex step of the Magical Method, as it required great talent and magical knowledge experience, the Experiment stage was the most dangerous.
This was where one would 'activate' the spell internally to find out if the sequence was stable. Here, if your Theory was extravagant and your Design sub-par, as well as filled with holes, you would be digging your grave more often than not.
For example, going back to the 'I want to cut off the heads of 100 men using the wind' example, one could have set it in the Design stage that wind blades would be released that randomly or specifically targeted the nearest 100 people.
However, a common mistake low-tier Journeymen with barely any talent/experience would make would be failing to exclude themselves!
As a result, one could easily end up as one of the '100 men' who would lose their heads!