Scoping
In JMeter, elements are organized in a tree, where each node has parents and children, which can be branches or leaves.
The scope of an element is based on where the element is located in the tree branch.
Simply defined, the scope of an element is composed of the elements that are children of its own parent.
In the following screenshot, the scope of Response Assertion, highlighted in red, includes the elements contained in the yellow rectangle; namely, all the child elements of the parent, Test Plan:
Figure 4.1: Scope
As a consequence, when the test is run, it will execute the assertion for every HTTP Request: