Final answer:
In high school physics, the head-to-tail graphical method is best for maintaining control over subsections when dealing with vertical or diagonal cutting lines.
Step-by-step explanation:
The best technique to use when you need to maintain control of a subsection while cutting a vertical or diagonal cutting line is the head-to-tail graphical method. This method involves drawing vectors sequentially such that the head of one vector touches the tail of the next. This allows for a clear and manageable representation of all vectors and their resultants, making it easier to maintain control when cutting lines either vertically or diagonally.