Imagine that you have a user 1 story that requires an implementation of a method:
public static void MyMethod(string paramA);
Several classes will use this method, and MyMethod does everything necessary to complete the history of user 1, but nothing more.
Are you sure that in the future iteration another story will come (user story 2), which will require the method to become:
public static void MyMethod(string paramA, int paramB);
Previous calls to MyMethod will need to be reorganized, and some new calls to MyMethod will need to be added in accordance with the requirements of user story 2 (Note after story 2 it never makes sense to call MyMethod only with paramA).
When working on user story 1, this is flexible thinking:
1) Only implement: public void MyMethod (string paramA);
2) : public void MyMethod ( paramA, int paramB); - . 0 .
3) : public void MyMethod ( paramA, int paramB); - . ( 2)
4) : public void MyMethod ( paramA, int paramB); - , 1 2