Imagine a biography about John. In the biography, in response to a question about after dinner activities, John's grandmother says:
"John will clean the kitchen, and the family will take a walk for 30 minutes."
Employing scholar's method of "exegesis", clearly (because John is the main subject by context - his biography), this should be understood as John cleaning the kitchen for 30 minutes while simulateously taking a walk for same amount of time. And even though the next paragraph in John's biography lists each family member on the walk (some 20+), the writer definitely didn't mean it as family, but rather the main subject (John) only on the walk.
Also, there is no way John could start cleaning 15 min into the walk, as it's not the family, but John only, it's all 30 min.